Found this...

[Goby-won]

anyone know what this thing is. I found it my sump tonight. Bottom, center left of light reflection.

 

[eliramos]

Do you have any anemones in your tank right now? It looks like a baby one of some kind, not sure if it's a bad one or not though. Hopefully someone else will chime in.

 

[Goby-won]

Thanks for the note, that's what I originally thought, but I have never seen them do this. In order to get in the chamber it would have had to make it through a filter sock, over one baffle, under another baffle and over one more. That is one tricky guy.

By the way - to answer your question: Two green and two red bta's plus one rock. Nem

 

[Lionfish Lair]

Nuisance anemones/appies are often found attached to macro. I would remove that.

 

[saltyfilmfolks]

I'd love a closer pic. Yea could be one of the fancy pretty Caribean appies or mojano but boy sure kinda looks like a baby BTA.

Fwiw my pink bubble coral one plate coral and a monto were hikers on live rock rubble. Looked like snot on a rock.
The bubble is three inches now.