Star ascidian  (Botryllus schlosseri)

Very common and widespread around the coasts of Britain. It also occurs around Ireland and in mainland Europe from the Faeroe Islands and Norway, reaching as far south as the Mediterranean. It is also known from the western Atlantic along parts of the coast of North America, where it is thought to have been introduced on the hulls of ships (2).

Typically occurs on the lower shore and in shallow depths, but has been recorded at depths of several hundred meters (2). It seems to fare particularly well in sheltered sites, such as docks, and grows on a wide range of stable substrates including rock, algae and artificial surfaces (2).