Glossobalanus marginatus is a species of acorn worm within the family Ptychoderidae.

[1][2][3] The species was first described from a specimen caught off the Northumberland coast on August 22, 1921, where its discovery extended the known range of acorn worms to the North Sea and coasts of British Isles.

[4] The species inhabits marine waters of the North Sea, Baltic Sea, and coasts of the British Isles.

[4][1][2] The species grows to a length of 15 millimeters.

[2]