unknown orange spikes

[stkitts]

I have hundreds of these short, brown with orange headed spikes growing of my live rock. They are about 1/4" long. They are hard to the touch. What are they?

 

[LeslieH]

These are vermetids. Vermetids are odd ball snails whose shells don't coil but instead form irregularly shaped tubes. They produce long strings of mucus which drift in the current & collect particles. The strings are pulled back in then digested. Harmless really, but they can multiply to plague proportions & some people feel their corals are irritated by the strings. Unfortunately the only way to get rid of them seems to be by hand, scraping or breaking off the tubes, or with a copperband.