Sand Dollars are a type of sea urchin that lived mainly in shallow water near land, where they like to bury themselves in sand.  While alive, Sand Dollars are covered with short fuzzy spines that almost look like fur, which are used to push plankton into the Sand Dollar's mouth (located on its under side).  Sand Dollars also use their spines to move along the sand or burrow into it.
From the late jurassic period, these specimens are approximately 150 million years old.
Measures: 2.5 inches across.