Molgula, or sea grapes, are very common, globular, individual marine tunicates roughly the size of grapes.[1]
They are translucent with two protruding siphons. They are found subtidally, attached to slow-moving submerged objects or organisms. All species of Molgula have a fluid-filled structure called the renal sac.[2] The renal sac contains nitrogenous wastes, solid concretions composed of weddellite and calcite,[3] and an apicomplexan symbiont called Nephromyces.[4]
In the western Atlantic Ocean, they range from the Arctic to North Carolina, to the center of the United States Eastern Seaboard.[5]