The Coleman Shrimp (Periclimenes colemani) has a unique symbiotic relationship with the rainbow urchin (Asthenosoma varium). The urchin provides a mobile home for the shrimp, complete with protection from predators via its highly venomous spines. In turn, the shrimp removes parasites from the urchin. The spines of the urchin can inflict a painful sting that can last for several hours, as I discovered the hard way during this dive in Anilao, Philippines. Read more in our post, Biodiversity from the Muck to the Reef: Scuba Diving Anilao, Philippines.