white tube worm

I run a JBJ 45 gal AIO set up. My reef is very clean with absolutely no algae. My water tests for nitrate and phosphate is always zero. I do feed with very small mysis shrimp so maybe small food particulates is feeding the tube worms; there's also a few sponge species in the back of my tank as...

I put my acans on a new rock together and now I found these white tubes on the skeleton. Any help in ID would be much appreciated.