any of various flat, disklike sea urchins, as Mellita testudinata or Echinarachnius parma, that live on sandy bottoms off the coasts of the U.S.
Origin of sand dollar
An Americanism dating back to 1880–85
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
any of various flattened disclike echinoderms of the order Clypeasteroida, of shallow North American coastal waters: class Echinoidea (sea urchins)
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012