Is this Aiptasia?

[Germanman]

yea they are totally benificial

 

[Bree]

Having seen aptasia and having coral in my tank that looks exactly like what you have posted I would say no. MY local fish store has it all over their coral tanks. It looks like clear brown little anenomes. Adding a link with very clear pictures of Aiptasia http://www.wetwebmedia.com/marine/inverts/cnidaria/anthozoa/aiptasia/aiptasia.htm
Great site and where I found the info on my sponges