Does anyone know what this is?

[JohninBurton]

I spotted this in my tank today and no idea what it is, it looks like a star fish. Can anyone help identify it please?

 

[DaJMasta]

Does it move or inflate? Sure does look like a starfish, but if it doesn't move around at all, it won't be. Could be something retracted that has yet to inflate, or it could look flat from this angle but not really be.

Behavior can be really helpful to point you in the direction of an ID, so maybe see if it moves, see if it changes shape, squirt some water at it with a baster, and maybe shine a light on it after dark and see if you get a response.

 

[JohninBurton]

Thanks for the advice
Its moving around slowly, about 3 inches in the last 4 hours. Its definetly not flat and appears a similar size now that the lights have all gone off.

 

[bblumberg]

Looks like an asterina star to me. These proliferate RAPIDLY. If you don't want that, remove it now.

 

[DaJMasta]

I would lean towards an asterina star too, then. Haven't seen one with the red bits, but they do come in a variety of colors.

A lot of people have "problems" with them as they do propagate and spread, but they've never grown at a huge pace in my tanks and there are relatively few species that actually eat corals or do something else we wouldn't want.

If the population explodes, there's always something like 'renting' a harlequin or bumblebee shrimp to clean the place up.

 

[fishface NJ]

asterina

 

[JohninBurton]

Thanks for the help guys, I'll try and find the critter today.