Gavin Hellier / Aerial shot tracking along chalk cliffs at sunset, near Old Harry Rocks, Dorset, England, UK, May 2017. Hellier

Chien Lee / Limestone rock formations, Snow Mountains, Papua, Indonesia

Chien Lee / Limestone pinnacles, Tsingy de Bemaraha National Park, Madagascar

David Noton / The Pinnacles at night, limestone formations. Nambung National Park, near Cervantes, Western Australia

Alex Hyde / Fairy's thimble flower (Campanula cochleariifolia) growing in a crack running through a limestone slab. Triglav National Park, Julian Alps, Slovenia. July.

Alex Hyde / European House Centipede (Scutigera coleoptrata) found on the ceiling of a limestone cave. Photographed on a white background in mobile field studio. Plitvice Lakes National Park, Croatia. November.

Alex Hyde / Close up of head of European House Centipede (Scutigera coleoptrata) in limestone cave. Plitvice Lakes National Park, Croatia. November.

Alex Hyde / Water cascading over naturally formed tufa dam. Tufa is a kind of limestone, formed from the precipitation of carbonate minerals which builds up around mosses and water plants to form a solid limeston...

Juergen Freund / Schooling silversides (Atheriniformes) split level with karst limestone cliff and West Papuan fishermen in their dugout outrigger canoe. Raja Ampat, Indonesia. Second Place in the Portfolio Award of t...

Juan Carlos Munoz / People exploring underground lakes via rigid inflatable boat, Cross Cave (Krizna jama) under Cross Mountain, Green Karst, Slovenia, October 2014.

Alex Hyde / European Cave Spider (Meta menardi) in limestone cave. Plitvice Lakes National Park, Croatia. January.

Alex Hyde / Cave Cricket female (Troglophilus cavicola) on the side of stalactite in limestone cave. Plitvice Lakes National Park, Croatia. January.