What is this?

Hmm...that's what I thought, too, but it's sitting next to another toadstool leather that looks nothing like it.
 
Toadstool leathers can vary quite a bit in flesh color, polyp color, and polyp / tentacle length. Do you have a pic of the one next to it?
 
The stupid PJ is in front of the one in question, but the toadstool is right next to it.

coral2.jpg
 
Yep, they're both toadstool leathers, just different varieties. As the smaller one grows larger, it'll start to get more of a ruffled edge like the larger one has.

Just a word of advice... You may want to think about relocating the frogspawn. The sting from the frogspawn can do a lot of damage to the toadstool leather, and it won't be long before one or both of them grow enough to be within range.
 
Thanks for the ID, and good advice on moving them. I have moved the frogspawn to the other side of the aquarium and moved the rock that the smaller toadstool is attached to, as well.

BTW: The smaller toadstool was just a hitchhiker on a piece of live rock so I guess I got a bonus there!
 
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