Sand Dollar

ocean · sea urchin · spiky creatures · sandy homes

Flattened shape. Sand dollars are sea urchins that have evolved to be incredibly flat instead of round, which helps them wiggle down into sand and hide from bigger ocean animals.

Sandy burrowers. They use their tiny spines and tube feet to dig into the ocean floor, where they spend most of their time munching on bits of food that float down through the water.

Yummy nicknames. People call them sand dollars, sand cakes, and cake urchins because their flat, round shape and bumpy pattern kind of look like a fancy dessert or coin.

Related sea biscuits. Some species in the same family aren't quite as flat as sand dollars, and these cousins are called sea biscuits instead.

Part of a big family. Sand dollars belong to a special order of sea urchins called Clypeasteroida, which all share that super-flat design for life on the ocean floor.