The alligator snapping turtle (Macrochelys temminckii) is one of the largest freshwater turtles in the world and the heaviest in North America. Adult males typically weigh between 70 and 113 kilograms (155 to 250 pounds), though exceptional individuals have been recorded weighing up to about 136 kilograms (300 pounds).

It has a thick shell with three distinct ridged spikes running along the back (carapace). These raised ridges and a camouflage of algae growing on its shell help it blend into murky waters. The turtle’s head is large and triangular with a strong, hooked beak. Its jaws are extremely powerful, capable of snapping through tough materials with ease. Unlike most turtles, it cannot fully retract its head into its shell, but it compensates with bony protective eyelids and fleshy, frilled skin that give it a prehistoric visage. This turtle’s coloration and texture help it hide exceptionally well.