Colin Monteath/ Hedgehog House / Parallel sand dunes in desert, Simpson Desert, Northern Territory, Australia

Constantinos Petrinos / Bigfin reef squid (Sepioteuthis lessoniana) schooling parallel to one another. Lembeh Strait, North Sulawesi, Indonesia.

Danny Green / 2020VISION / Adder (Vipera berus) coiled, basking on moss in the spring sunshine, Staffordshire, England, UK, April. Photographer quote: "OK so snakes are perhaps not as sexy as seals or foxes but I just can't get...

Nick Upton / Arable field with young Maize / Sweetcorn seedlings (Zea mays) growing in neat parallel rows, Wiltshire, UK, late spring 2009

Yva Momatiuk & John Eastcott / Small sandstone canyon carved by water, exposes strong pattern of parallel lines, Vermilion Cliffs National Monument, Colorado Plateau, Utah

Heather Angel / Bamboo growing beside narrow mountain track. Gaoligongshan National Nature Reserve, Three Parallel Rivers of Yunnan Protected Areas, Yunnan Province, China. May 2009. Digitally stitched panorama.

Heather Angel / Peaks and clouds above Tiger Leaping Gorge at dawn. Three Parallel Rivers of Yunnan Protected Areas World Heritage Site, Yunnan Province, China. 2010.

Yashpal Rathore / Kambala racing, a buffalo race which takes place on two parallel slushy tracks. Karnataka, India.

Staffan Widstrand / Wild Wonders of China / Autumn trees and habitat in UNESCO World Heritage Site 'Three Parallel Rivers', Baima Snow Mountain Nature reserve, Yunnan, China, October 2017.

Staffan Widstrand / Wild Wonders of China / Autumn landscapeof the wilderness in the UNESCO World Heritage Site 'Three Parallel Rivers', Baima Snow Mountain Nature Reserve, Yunnan, China, October.

Graham Eaton / En echelon tension (or parallel) cracks in Carboniferous age turbidite sandstones, Bude, Cornwall, UK, May. The tension cracks have formed in the more competent sandstones as the rocks were folded. T...

Graham Eaton / Merrivale stone rows, a line of upright, parallel megalithic standing stones, Devon, England, UK, May.

Constantinos Petrinos / Bigfin reef squid (Sepioteuthis lessoniana) schooling parallel to one another. Lembeh Strait, North Sulawesi, Indonesia.

Constantinos Petrinos / Bigfin reef squid (Sepioteuthis lessoniana) schooling parallel to one another. Lembeh Strait, North Sulawesi, Indonesia.

Constantinos Petrinos / Bigfin reef squid (Sepioteuthis lessoniana) schooling parallel to one another. Lembeh Strait, North Sulawesi, Indonesia

Graham Eaton / Eglwseg Escarpment, dipping beds of Carboniferous, Dinantian age limestone. Back of hill parallel with bedding layers with scarp face eroding through the beds, Llangollen, Wales, UK,

Graham Eaton / Eglwseg Escarpment, dipping beds of Carboniferous, Dinantian age limestone. Back of hill parallel with bedding layers with scarp face eroding through the beds, Llangollen, Wales, UK, September 2016

Graham Eaton / Rotated normal fault in Cretaceous chalk with erosion, small caves at base. Chalk beds vertical and parallel with the cliff, Durdle Door, Jurassic Coast, Dorset, England, April 2012.

Yashpal Rathore / Blackbuck (Antelope cervicapra) males walking parallel during rut, Tal Chhapar Wildlife Sanctuary, Rajasthan, India

Tony Wu / Sperm whale (Physeter macrocephalus) male with lots of long parallel scars on its forehead from fights with other males, Ogasawara or Bonin Islands, Japan.

Tony Wu / Sperm whale (Physeter macrocephalus) male with lots of long parallel scars on its forehead from fights with other males, Ogasawara or Bonin Islands, Japan.

Tony Wu / Sperm whale (Physeter macrocephalus) male with long parallel scars from fights with other males,Ogasawara or Bonin Islands, Japan.

Tony Wu / Sperm whale (Physeter macrocephalus) male with long parallel scars from fights with other males,Ogasawara or Bonin Islands, Japan.

Colin Monteath/ Hedgehog House / Parallel sand dunes in desert, Simpson Desert, Northern Territory, Australia

Colin Monteath/ Hedgehog House / Parallel sand dunes in desert, Simpson Desert, Northern Territory, Australia

Colin Monteath/ Hedgehog House / Parallel sand dunes in desert, Simpson Desert, Northern Territory, Australia

Constantinos Petrinos / Bigfin reef squid (Sepioteuthis lessoniana) schooling parallel to one another, Lembeh Strait, North Sulawesi, Indonesia.

Constantinos Petrinos / Bigfin reef squid (Sepioteuthis lessoniana) schooling parallel to one another. Lembeh Strait, North Sulawesi, Indonesia. COMPOSITE

Thomas Lazar / Common loon (Gavia immer) fledgling crouching with head and neck parallel to water in territory / alarm display. Turtle Flambeau Scenic Waters Area, Wisconsin, July.

Thomas Lazar / Common loon (Gavia immer) swimming with fledgling. Crouching with head and neck parallel to water in territory / alarm display. Turtle Flambeau Scenic Waters Area, Wisconsin, July.

Thomas Lazar / Common loon (Gavia immer) pair swimming with fledgling. One adult crouched with head and neck parallel to water in territory/alarm display. Turtle Flambeau Scenic Waters Area, Wisconsin, June.

Igor Shpilenok / Parallel tracks of a person and a Wolverine (Gulo gulo); the Wolverine is adapted to easily walk over snow. Kronotsky Zapovednik Nature Reserve, Kamchatka Peninsula, Russian Far East, February.

Philip Stephen / Parallel rules on navigation chart aboard trawler on the North Sea, 2010.

MYN / Paul Harcourt Davies / Spruner's Ophrys orchid (Ophrys spruneri) an orchid endemic to Southern Greece with a wide distribution. Has same pollinator as (Ophrys sipontensis) in Gargano, Southern Italy that has effected parall...

MYN / Paul Harcourt Davies / Spruner's Ophrys orchid (Ophrys spruneri) an orchid endemic to Southern Greece with a wide distribution. Has same pollinator as (Ophrys sipontensis) in Gargano, Southern Italy that has effected parall...

MYN / Paul Harcourt Davies / Spruner's Ophrys orchid (Ophrys spruneri) an orchid endemic to Southern Greece with a wide distribution. Has same pollinator as (Ophrys sipontensis) in Gargano, Southern Italy that has effected parall...

MYN / Paul Harcourt Davies / Spruner's Ophrys orchid (Ophrys spruneri) an orchid endemic to Southern Greece with a wide distribution. Has same pollinator as (Ophrys sipontensis) in Gargano, Southern Italy that has effected parall...

Aflo / N-4305 Woodland tree trunks, Japan

Aflo / N-0705 up double trunks of tree into canopy, Shirakami-Sanchi, Akita, Japan.

Nick Upton / Aerial view of young arable crop sprouting in neat parallel rows, with fence line and a few small trees separating two fields, Wiltshire, UK, spring.

Nick Upton / Arable field with young Maize / Sweetcorn seedlings (Zea mays) growing in neat parallel rows, Wiltshire, UK, late spring 2009

Nick Upton / Aerial view of young arable crop sprouting in neat parallel rows, with fence line and a few small trees separating two fields, Wiltshire, UK, spring.

Jerry Monkman / 45th Parallel sign in Sterwartstown, New Hampshire, USA. October 2007

Luiz Claudio Marigo / Aerial view of Madeirinha River that flows parallel to the Madeira River, and lakes of its floodplain ("várzea") with different colours of water, at Northwest of Borba town, Amazonas State, Northern...

Edwin Giesbers / Antarctica - map / chart and mapping instruments including dividers and parallel rulers

Roger Powell / Pair of Griffon Vultures {Gyps fulvus} parallel flying in courtship, Sierra de Grazalema, Andalusia, Spain

Rob Tilley / Stand of Quaking Aspen Grove {Populus tremuloides} White River NF, Colorado, USA

Roger Powell / Pair of Atlantic puffins {Fratercula artica} standing on rock. Farne Islands, UK.

Onne van der Wal / Man navigating with chart and parallel rule on a table in the cabin of a yacht.

Roger Powell / Bearded vulture (Gypaetus barbatus) pair, flying in close parallel formation, courtship display, Lamiana, Aragon, Spanish Pyrenees, Spain. April.

Enrique Lopez-Tapia / View of Gangdise snow-capped summits, mountain range parallel to Himalayas, in clouds. Tibetan Highlands, China. May, 2016.

Enrique Lopez-Tapia / View of Gangdise snow-capped summits, mountain range parallel to Himalayas, in clouds. Tibetan Highlands, China. May, 2016.

Roger Powell / Pair of Bearded vultures (Gypaetus barbatus) engaging in courtship display, flying in parallel. Lamiana, Aragon, Spanish Pyrenees, Spain. April.

Manuel Gracia / Tracking shot of an Iberian lynx (Lynx pardinus) juvenile male jumping out of a thicket and walking parallel with the woodland fringes, in search of food. Then the animal disappears into the undergrow...

Alejandro Prieto / Aerial view of the parallel bars at Marismas Nacionales, the largest mangrove coastal ecosystem in the Mexican Pacific and habitat for the Jaguar, Nayarit, Mexico. October.

Alejandro Prieto / Aerial view of the parallel bars at Marismas Nacionales, the largest mangrove coastal ecosystem in the Mexican Pacific and habitat for the Jaguar, Nayarit, Mexico. October.