They, along with starfish, are called echinoderms, pronounced eek-AYE-no-derms.
The structural deference between them is that Sea urchins are more globular whereas sand dollars are flattened. Unlike sea urchins, the sand dollars burrow themselves when threatened. Sand dollars have anus opening at their back side whereas the sea urchins have it at the top.
sea stars, sea urchins, sand dollars, and sea cucumbers.
Sea urchins and sand dollars.
No. They are invertebrates related to starfish and sea urchins.
Yes they are. They are flattened burrowing sea urchins.
Star fishes and sea urchins are similar to sand dollars.
They both or found in the ocean
Echinoderms include sea stars, sand dollars, sea cucumbers, sea urchins, etc.
Echinoderms, which include star fish, sand dollars, and sea urchins have an oral plate.
No - sea urchins are part of the echinoderm phylum, with sand dollars, starfish and sea cucumbers.
Echinoderma are a phylum of "spiky skin" sea life, such as starfish, sea urchins, and sand dollars.
Sand Dollars are the carcasses of dead sea urchins, and when alive, they eat though a mouth.