New unknown critter

[ghill]

Showed up a couple of weeks ago. Has grown to about 1" diameter. Have not added any fish or corals in over 6 weeks. Mostly a light green with some orange showing up where it meets the gravel. I think it is some kind of coral but I didn't order it. Any thoughts? Thanks.

 

[JTP424]

The little green spiral guy?
Looks like a mushroom!
If you used live rock or ocean gathered just a hitchhiker.

 

[Oldreefer44]

Yes is a mushroom coral. If you don't want a lot of them, remove it. They can multiply very quickly.