Canreef Aquatics Bulletin Board

ok so today when I went to turn on the actinics, I saw this worm like thing show half of its body from out side my rocks...its really small like about 5mm in diameter and showed like about 1cm outside the rocks. it looked almost like a tube of a tube worm but was not a tube worm beause I saw no crown/feathers. It was creamy white in color. When it when out it released some kind of smoke like cloud into the water. I m not really concern about what it is, i dont think there is a way I can get him out anyways unless I dismantle my rocks. The thing that I am really concern about is that smoke that he released. could it be toxins??? has anyone had something similar???