"A Christmas Tree Worm lives in a tube. The tube is like a shell that it builds on the surface of a coral. Then it sticks its head out of the tube."
Christmas Tree Worm on Star Coral, Grand Turk
"Corals shelter many kinds of invertebrates, such as this Christmas-Tree Worm. This worm builds a tube on the surface of the coral, and as the coral grows it buries the tube in the skeleton of the coral. Then the worm is protected with only its head showing."
Christmas-Tree Worm
"The lovely flower-like Christmas tree worm ranges throughout Florida, the Caribbean, and the Gulf of Mexico. Growing up to four inches, the round conical worm does resemble a Christmas tree, or many times a pair of Christmas trees. These worms live in a calciferous tube which shelters their whole body. The tube is attached to either live or dead coral."
Christmas Tree
"Much of the worm is anchored in its burrow, a hole bored into a live calcareous coral."
Christmas tree worm, Spirobranchus giganteus
"The reason that the worms are found on specific corals seems to be a result of larvae showing a strong settlement preference for corals such as Porites asteroides and Millepora complanata and ignoring corals such as Siderastrea, Dendrogyra and Agaricia. However, when researchers examined the growth and survival rates of worms on different coral species, worms that settled on Diploria strigosa did the best, followed by those living in Montastrea annularis, M. cavernosa, and Porites porites came in dead last in every measure of growth for the worms!"
"As far as I can tell from the research done on these worms, the primary reason that they are found almost entirely in association with live corals has nothing to do with nutrition. In fact, researchers have examined the boring invertebrate communities in corals that are live, to those in which 50%, or 100% of the colony was dead, and they found big differences. In living corals, only 3 species were commonly found (a bivalve, a vermetid snail and the Xmas tree worms)."
Reefs.org: Where Reefkeeping Begins on the Internet - Porites and 'Christmas Tree Worms'
Doc, I can go on and on with references. Are you ready to concede that Christmas tree worms burrow into and live off of live corals? Or do you need more *convincing*??