The Medusa Worm, Loimia medusa, is a unique marine invertebrate that is actually a type of sea cucumber. Their skin is comprised on sticky skin cells that allow it to stick to any surface. Generally, Medusa Worms are tan or green in color. They are beneficial tank mates to help keep things clean and are particle feeders that do not require supplementary feeding. Caution should be exercised housing Medusa Worms - they can secrete a deadly toxin if stressed out or injured so they should not be kept with anything that may harm them. Medusa Worms are fast growers and can grow quite large in home aquariums.