Sand dollars live in groups on the sandy ocean bottom in shallow water. Live ones are prevalent on Sanibel Island on the Florida gulf coast, but it is illegal to collect live shells.
The one to the left is called an Arrowhead.
Below the Arrowhead is the puffy sand dollar, shown here in sepia tone, and is known as a Sea Biscuit. This one is about 5 inches wide. Other sand dollar types include “flat round”, “pancake” and “sea gopher”. There is a smaller puffy sand dollar called a “cookie”.
Sand dollars are inexpensive to buy. Here are some links I’ve found to Seashell suppliers.
Seashell World *** Deltona Seashells *** Caribbean Imports
