Mark Payne-Gill / Three banded armadillo rolling up into defensive ball {Tolypeutes tricinctus}. Very tough skin consists of double layer of horn and bone

Mark Payne-Gill / Three banded armadillo rolls up in defensive ball {Tolypeutes tricinctus}

Mark Payne-Gill / Brazilian three banded armadillos rolled up in defensive ball {Tolypeutes tricinctus} - head and back view. Articulated tough skin in hinged bands allow flexibility

Naskrecki & Guyton / White-backed vultures (Gyps africanus) feed in a frenzy at a waterbuck carcass (Kobus ellipsiprymnus), Gorongosa National Park, Mozambique. Waterbuck are large animals with tough hides, and in Gorongo...

Jeff Vanuga / Grizzly bear (Ursus arctos horribilis) emerging from den after hibernation. Grand Teton National Park, Wyoming, USA. April.

Ashley Cooper / Highland cattle, with snowfall, Kirkstone Pass, Lake District, England, UK, December 2008.

Jen Guyton / White-backed vultures (Gyps africanus) and spotted hyenas (Crocuta crocuta) squabble over the drying and deflated skin of an elephant carcass (Loxodonta africana), Laikipia Plateau, Kenya. The hyenas...

Nick Upton / Cotham marble / Landscape marble boulder, a tough limestone with attractive landscape-like patterns when polished, formed from fossilised cyanobacterial stromatolites, exposed by river action, Lower w...

Terry Whittaker / 2020VISION / Konik horse (Equus caballus) grazing on tough grasses on Wicken Fen, Cambridgeshire, UK, June 2011

Pete Oxford / View of the Savannah grasslands through a shattered windscreen, Rupununi, Guyana, March 2010

Solvin Zankl / Olive ridley sea turtle hatchling (Lepidochelys olivacea) showing egg tooth that helps the hatchling to open the soft but tough egg shell. Ostional beach, Costa Rica, November

Aflo / N-18306 Camelia Sasaanqua flower in snow, Japan.