Jennifer Plummer, age 13, of West Scarborough, Me., for her question:

WHAT IS A SAND DOLLAR?

A sand dollar is an animal that you’ll find in shallow coastal waters. He is thin, flat and circular. He’s about two to four inches wide and looks very much like a puffed up silver dollar or cookie.

The sand dollar’s body is usually covered with slots or notches. On top you’ll find a set of breathing tubes that are arranged in the form of a five point star. The creature’s body is covered with tiny movable spines which are used for crawling and digging.

Burried in the sand most of the time, the sand dollar lives on tiny bits of animals and plants that he finds among the grains of sand. Food travels along the grooves on the underside of his body to his mouth in the center of the under surface. He’s an echinoderm.