Polymastia penicillus

[1] It is found in shallow water in the northeastern and the northwestern Atlantic Ocean, growing on rocks in areas of high sedimentation.

A number of hollow, cylindrical papillae up to 3 cm (1.2 in) long project from the upper surface, with an osculum (exhalant opening) at the tip of each, and many small inhalant pores on the sides.

Its typical habitat is on rock near to sandy areas, and where there is much suspended particulate matter in the water.

Sexual reproduction takes place during the summer, the larvae being expelled with the water current and soon settling on the seabed to become juveniles.

This has a very large genome, which includes several bioactive clusters of genes and many mobile DNA elements; these may enable the bacterium to survive in various hosts and habitats by exchanging genetic material.