#ed_op#DIV#ed_cl#There are these hard tube shaped growths about 1/2 inch long that seem to grow on the rocks. As far as I can tell there is nothing in them just an empty tube. What are they? What should I do about them? Are they good/bad/indifferent? #ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl##ed_op#/DIV#ed_cl##ed_op#DIV#ed_cl##ed_op#IMG alt="image file name: 2kbc70ba85e4.jpg" src="http://www.captivereefing.com/richedit/upload/2kbc70ba85e4.jpg" border=0#ed_cl##ed_op#/DIV#ed_cl#