Frederique Olivier / South polar skua (Stercorarius maccormicki) chick at nest site feeding from a piece of eggshell, Antarctica.

Ingo Arndt / Olive ridley sea turtle (Lepidochelys olivacea) empty eggshells on the beach, Pacific Coast, Ostional, Costa Rica.

Markus Varesvuo / Capercaillie (Tetrao urogallus) nest with eggshells left behind after chicks hatched, Vaala, Finland, June.

Markus Varesvuo / Female Capercaillie (Tetrao urogallus) with three newly hatched chicks and broken eggshells, Kuhmo, Finland, June.

Scott Leslie / Snapping Turtle (Chelydra serpentina) nest cavity with eggshells, Canada

Juergen Freund / Leatherback turtle (Dermochelys coriacea) nest dug out by natural predators such as monitor lizards, wild boar or night herons. Warmamedi beach, Bird's Head Peninsula, West Papua, Indonesia, July 2009...

Jane Burton / 2-day-old chicks {Gallus gallus domesticus} finding wheat grains among straw, with hatched eggshells.

Klaus Nigge / Masai ostrich (Struthio camelus massaicus) nest with eggs and eggshells, Tarangire National Park, Tanzania.

Klaus Nigge / Masai ostrich (Struthio camelus massaicus) nest with eggs and eggshells, Tarangire National Park, Tanzania.

Tui De Roy / Leatherback turtle (Dermochelys coriacea) hatchling swimming across a rainwater pool, littered with empty eggshells, toward the sea minutes after leaving the nest, Grande Riviere, Trinidad Island, Tri...

Nick Upton / Marsh fritillary (Euphydryas aurinia) caterpillars, newly hatched, eating eggshells as others begin spinning a silken larval web over Devil's bit scabious (Succisa pratensis) leaves, their larval food...