Help identify please!

I think this little guy made his way into my tank attached to some live rock I got from a friend, can anyone help identify? It's only about the size of my pinkie nail.

 

It is an Asterina star, most are harmless grazers.

Some populations can explode.

Some eat zonathds, coralline and rarely a coral. There are hundreds of different types.

Unless you witness it eating corals or see damage I would let it be.

 

Thank you! I was hoping I wouldn't have to get rid of him, I like him! So I don't really have to do anything with him? He'll just kinda find his own food and stuff?

 

Yeah pretty much.

I have found the grey ones found on the glass to be harmless as they are simple algae eaters. Blue or purple ones can be coralline eaters. I have them eat zoanthids as well but as stated most are harmless.

They reproduce by lateral fission, basically just splitting down the middle, this makes number of appendages an inaccurate way to ID type.