What is this coral and why does it have a bubble?

[mccusker1818]

I've had this coral for almost a year, it had developed this bubble over the last month or so. Similar to a trachyphyllia, but it's not.

 

[fishguy242]

stony body ? not a mushroom??...

 

[mccusker1818]

stony body ? not a mushroom??...

Correct. Here's an old picture.

 

[fishguy242]

indophyillia , lobo ? have seen bubbles on lps before ,just appear and disappear.
check at tissue line to be sure nothing has burrowed under tissue

 

[Wasabiroot]

That looks like a lobo, I agree. 2nd pic looks almost like a rhodactis; I was like "if that was a mushroom lady luck is on your side"

 

[mccusker1818]

indophyillia , lobo ? have seen bubbles on lps before ,just appear and disappear.
check at tissue line to be sure nothing has burrowed under tissue

Nothing under the tissue. Just checked.

 

[ISpeakForTheSeas]

No idea on what the coral is, but here's what I've found on the bubbling:

I don't know if this is related or not, but it reminds me of when corals "bounce" unexpectedly (such as the acans discussed below):

They're basically joking that you've either got two corals or a "bounce" acan that would be potentially be valuable.

The only thing I can find on this condition is that it may potentially be caused either by some kind of high lighting (some people say LED's, others UV; it's basically thought to be similar to sunburn reaction in people) or by elevated potassium levels, and it doesn't seem to negatively impact the corals in any way (but the bubbles if popped are prone to infection):
https://www.reef2reef.com/threads/bubbling-acanthophyllia-and-acan.570958/https://www.reef2reef.com/threads/flesh-bubbles-on-acan.184931/https://www.reef2reef.com/threads/odd-bubble-in-acan-bower-tissue.224346/https://www.reef2reef.com/threads/bounce-acans-micros.913841/https://www.reef2reef.com/threads/bounce-acan.488798/https://www.reef2reef.com/threads/bouncing-acan.707112/https://www.reef2reef.com/threads/bounce-acan-what-could-be-causing-this-phenomena.538851/

So, it may be high lighting/UV or it may be elevated potassium; I've also heard of this happening to a number of other LPS corals (including different hammers), with suspected potential causes such as: coral starvation/lack of nutrients in tank, coral overfeeding, lack of flow, and toxins and/or activated carbon. No one seems to know for certain what causes it, though, and it doesn't seem to be harmful.
https://www.reef2reef.com/threads/sick-hammer-coral-help.276558/https://www.reef2reef.com/threads/swollen-torch-hammers-frogspawn.622793/https://www.reef2reef.com/threads/why-is-my-hammer-all-puffy.709222/https://www.reef2reef.com/threads/swollen-hammer.367813/