Molgulidae Lacaze-Duthiers 1877

Body usually sessile; often unattached and living buried in sand or mud. Test often covered with hair-like processes, and with much adherent sand or mud. Branchial aperture commonly with about six lobes, atrial with four lobes or square. Branchial sac with five to seven folds on each side; in some genera these are obsolete and indicated only by a small group of internal longitudinal vessels or a single large one. Stigmata mostly in large spirals, sometimes very perfectly formed and raised into inwardly projecting conical infundibula. Dorsal lamina continuous, often with a dentate margin. Stomach elongate, a part of its wall modified into a glandular organ. Usually one large hermaphroditic gonad on each side. A large closed renal sac on the right side of the body. (Van Name 1945: 219)

Molgulidae is a family of tunicates in the class Ascidiacea. Following a revision in 2007, the family Hexacrobylidae was synonymized with Molgulidae.