- Soft (non-reef forming), branching coral that grows attached to hard surfaces, forming carpets.
- Cylindrical (2-4 mm) branches have multiple polyps, which have eight white, frilly tentacles when extended.
- Colonies cannot grow in direct sunlight. It can be found in shaded areas such as under ledges, in crevices, harbors, and in deeper water.
- Native to the Caribbean, believed to be introduced to Hawaii and spread around the islands by hull fouling. First discovered in Pearl Harbor in 1972
- Spreads vegetatively (runners spread to adjacent areas), and by producing young that float to new areas (as planktonic larvae). Continues to spread when boats carry colonies to new locations (hull fouling)
- Overgrows corals and hard reef surfaces, preventing other species from growing. Can grow up to one inch every two weeks
- Colonies eat large amount of zooplankton – tiny animals which support the food web
- Colonies growing in deep water are overgrowing and killing black coral and large swaths of the bottom-dwelling community
- Present in large numbers in waters around most of the main Hawaiian Islands although the population appears very limited on Kauai. Small population on Kauai at Port Allen may be eradicable
- Not yet known to be present in the Northwestern Hawaiian Islands