Halofolliculina corallasia

Halofolliculina corallasia is a species of heterotrich ciliates identified as a cause of the syndrome called skeletal eroding band (SEB). It is the first coral disease pathogen that is a protozoan as well as the first known to be a eukaryote; all others identified are bacteria. Like other members of the folliculinid family, H. corallasia is sessile and lives in a "house" called a lorica, into which the cell can retreat when disturbed. The mouth is flanked by a pair of wing-like projections that are fringed with polykinetids, groups of cilia that work in groups to produce a current that draws food into the "mouth".

This species is so far the only known agent causing skeletal eroding band, the most common disease of corals in the Indian and Pacific Oceans, and also found in the Red Sea. A very similar disease was later discovered in the Caribbean Sea, but is caused by a different species of the same genus and occurs in a different type of environment.