ID on "aiptasia-like" creatures

[Pineapple House]

I've been noticing, in the last two months, these strang little "anemones" or "polyps" starting to grow and spread throughout the tank. These guys multiply quite fast, and seem like they can pack a sting. They're only the size of a pin head, and no larger. I've been injecting some with calcium hydroxide to keep them away from any neighboring corals, but, this doesn't seem to be working very well.

Any ideas on what this could be?

Thanks,
Graham

[phistio]

they look like Parazoanthus or "sponge zoanthids". they do have a bit of a sting to them, but are reef safe. most are not photosynthetic, but some may contain zooxanthallae.

they tend to grow rapidly when given strong currents, lighting and food...hence why they've grown so rapidly in your tank... :wink:

[michealprater]

They look like really small majanos to me. We will have to see if they get any bigger.