what are these?

[mystrybird]

<a href=showthread.php?s=&postid=10961006#post10961006 target=_blank>Originally posted</a> by dc_909
Unfortunately those bottom brown ones are colonial hydroids. They spread QUICK. I would take a piece of putty an completely cover that colony and any others.

Sorry to drag this back up. But I was just thinking. Would a drop of super glue gel work the same if you have just one or two in a small area? Thanks

 

[dc_909]

I would think so, but you would have to be able to remove the rock.