This is a what you see is what you get listing for this exact coral colony.
Christmas Tree Worm
(Spirobranchus giganteus)
Bisma worms, also known as Christmas Tree Worms, are a small variety of sedentary, tube building, fanworms. They burrow into live colonies of Porites coral where they activley wait for food passing through the strong current that is required for porites. They are extremely sensitive to anything encroaching on their environment and will quickly retract into their tube, closing their operculum, if threat arises.