Help identifying this leather

[klr0808]

So I’m fairly sure this is a neon toadstool but what makes these different from the ones that have the stalks? I would like to place one of these where My clown fish have somewhat hosted a rock. So I love this one, but I’m wondering if the stalk is just buried in the sand or if there’s a different species that grow flat like this instead of tall.
Also, is it not ideal to place these lower because of CUC and he is getting irritated with being touched?
Thanks.

 

[Rocks reef]

Looks like an aussie green polyp crown leather