Yes, aiptasia. Check out this thread, lots of great info and suggestions on it:
Aiptasia: taking care of business
Brilliant Oxy, great link. I've just had a quick scan through the thread and I like the idea of the biological control over the chemical. At present I can only see two anemones so maybe a peppermint shrimp if I can find the right species. Copperband butterfly is on my reserve fish species list but would I lose my little tube worms and other small inverts with a copperband? Also mine is a very new tank so probably not a good idea to put something like a copperband in at this stage.
I will have to see what the LFS has.....