Urgent Aiptasia or?...

They seem to be nocturnal as I only find them with a flashlight at night. They have redish bodies with clear tentacles with small white balls on the end of each one, each tentacle has this ball so it leads me away from aiptasia since I've never seen one like this. Also they dont protrude much from the rock they just seem to since flat against it but from a top down view do have some sort of red body.

Their appearance leads me to believe it is a type of ball anemone...which leads to the question are they good or bad...I've read both opinions. They are only about the size of a penny at the biggest.

Sorry but this is the best I could get in the dark, its in the center of the pic and you cant see the tentacles

 

from what i can see it just may be filter feeding worms ,if so they are desirable, asp nems are not scared of light they live off of it, ffw may not like light, i wish i had a tank full of them but my cbb fish eats them very fast, i don't think you have anything to worry about there.

 

Hard to tell from your picture, but from your description I would say it is something from the Pseudocorynactis genus. They can be nocturnal and have the features you describe

 

I thought the rock on the bottom was a big bug at first. Gave me the willies.

 

;D Thanks........ this thread has helped me id an unknown in my tank this morning. . the sugestion of the Pseudocorynactis genus led me to a search on google maybe this page will help you to.
Pseudocorynactis caribbeorum - Google Search

 

Yea guys, I have determined they are pseudocorynactis. They arnt big enough to hurt any of my fish and it appears some people actually purposely feed them and keep them.

 

i named mine Lebron, he stretched out from his hole at night time and slam dunks the sand scooping it up and sifting through it, creepy as hell but from what i can tell, they are harmless feeding on detritus

 

sponges