Epibiosis is any relationship between two organisms in which one grows on the other but is not parasitic on it. This picture shows the epibiosis by the barnacle Balanus crenatus on Carcinus maenas. The long intermoult period in older crabs can lead to a excessive colonization by epibionts, which could be harmful for the crab. This specimens were taken in the Wadden Sea, near to Texel, the Netherlands.