Help Identify this free goodie.

[proudnewbie]

Hey All.

Brand new to the forum. So let me start off saying Hey All

So I bought a piece of live rock today that had 5 heads of green rhodactis.
an the back side of the same rock was this little fellow. Can anyone help me confirm what it is. I believe it to be some kind of actinodiscus.
Anyways thanks all and I look forward to reading up on the forum
[IMG][/IMG]
http://s15.postimg.org/fgw43uquj/IMG_2129.jpg