(De Kay, 1843)
Description
External appearance
Solitary. Body globular to ovoid, up to 30 mm in diameter. Test grey to greenish, bearing fibrils with adhering sand, shells, etc..
Characters
Oral siphon 6-lobed; atrial siphon 4-lobed. Siphons diverging but close together at base. About 12-16 branched branchial tentacles of variable size. Branchial sac with numerous rows of curved and spirally arranged stigmata; six branchial folds on each side; longitudinal bars present. Gut left of branchial sac; stomach narrow and small, not marked off from rest of gut, bearing many diverticula forming a complex liver. One ovoid gonad on each side, consisting of a central ovoid ovary with marginal male follicles. Oviduct short and directed towards the atrial siphon (M. manhattensis morphology).
Habitat
Attached to hard substrata or loosely attached on sandy bottoms; from lower shore to depths of about 90 meters.
Distribution
From Norway to Portugal.