Echinarachnius parma

Echinarachnius parma is commonly known as the sand dollar. It is a species of flat, burrowing sea urchin that belongs to the order Clypeasteroida. These marine animals are famous for their distinctive, rigid, disk-shaped skeletons.

This species is widely distributed across the Northern Hemisphere. They typically inhabit the sandy or muddy bottoms of temperate and boreal ocean waters. You can often find their empty, white shells washed up on beaches in North America and Europe.

As an invertebrate, it burrows into the sand and uses its tiny, Velcro-like spines to move and capture food. It primarily feeds on organic particles, algae, and crustacean larvae found in the substrate. The spines help sweep the food along specialized grooves on its underside toward its central mouth.

Yes, despite their flat shape, sand dollars are a type of sea urchin. They belong to the order Clypeasteroida, which differentiates them from the rounder, spiny sea urchins found in tide pools. Their flattened body is an evolutionary adaptation for burrowing into soft ocean sand.