Caribbean Sea Mat?

[FireEater]

This was given to me by a friend because it was not doing good in his tank. He said it never opened up. It is the size of a golf ball.

He said it was called a Caribbean Sea Mat, yet when I Google it, I get Zoas, since they are referred to as sea mats.

Anyone have a clue to what this is, pictures, and where to place it?

 

[cloak]

Maybe this link will help.

http://www.advancedaquarist.com/2003/2/inverts

 

[FireEater]

Thanks! So far as I can tell, which is where the link led me eventually, is that it is Palythoa caribaeorum.

White Encrusting Zoathid

Large colonies of White Encrusting will inhabit shallow or deeper areas where they grow over hard substrates. They are white to creamy-yellow and shades of brown in color. Their oral cavities close when not feeding or if disturbed.

Now to move it around in different areas to see if I can get it to open up.