Jelly bryozoans are colony-forming bryozoans, where the colonies resemble thick branched cartilage fingers. They attach to seaweed, stones, shellfish or crab shells. The shape of the colonies can vary greatly and are sometimes incomparable with anything else. Some biologists just refer to them as 'a marine thing' instead of their name. There are several species of jelly bryozoans, but the transparent species is the most common. The different species are often only recognizable under the microscope. Colonies that have broken away from their underground are regularly found on the beach. Jelly bryozoans are common in the North Sea.