Just as radial symmetry is most noticeable in sea stars, sea stars are also the most well known of all echinoderms. Sea stars live in all oceans and in virtually all zones within the reef. 

While sea urchins may be considered the brutes of the echinoderms, feather stars are the delicate flowers of the group. 

Although they look similar to the sea stars, there are some major morphological differences between these two groups. 

Like the brittle stars, sea cucumbers perform a valuable function by constantly removing detritus from the substrate.