What do echinoderms look like?

Echinoderms are often brightly and variably colored.  They show their radial symmetry in much the same way as the spokes of a bicycle wheel radiate from the center and they exhibit short or long spines.  Starfish and brittle stars look like stars, many sea cucumbers look like actual cucumbers found in the supermarket, and sea urchins and sand dollars are very spiny.