The common moonsnail is the largest of several species of moonsnails that occur on the Atlantic coast. Moonsnails are saltwater snails that are found in many parts of the world. Moonsnails range from the Gulf of St. Lawrence to North Carolina, burrowing into sand, mud or gravel on the ocean bottom, usually at depths of 30-75 metres.

Common moonsnails have a rounded shell that is smooth to the touch and an enormous foot that they use to dig into the ocean floor. Their shell is off-white to tan. Common moonsnails grow quite large, to a diameter of about 10 centimetres. Moonsnails are infamous for preying on clams by drilling a hole into their shell and injecting them with a digestive juice that dissolves their flesh.