They catch the pray and feed the whole colony. Colonies living on a gastropod shell are either female or male. Basal tube-like branches, so called stolons, connect the polyps with each other.
Stolons are nesessary for the exchange of nutritions.
There are also certain hints that not only food is exchanged but also information. Spawning of the colonies is synchronized by the light cycle. Eggs and sperm are released into the water column. After fertilization a planula larva is formed within three days. In fully grown planulae all developmental specific actions like morphogenesis, cell differentiation and cell proliferation stop.