Holes in Lobophyllia skeleton

[Tschonas]

Hi guys,

today, I discovered some holes on the skeleton of my Lobophyllia.

On one side of the skeleton, there is some big round and deep hole. (Picture 1)
On the opposite side, it looks like a more extensive part of the skeleton has been hollowed out, with small, deep holes. There is also a yellow sponge next to the holes. (Picture 2)

Do you have any idea what the cause could be and what I could do against it?

The coral itself doesn't look all that bad in principle. A lot of small critters are living next to her, but I would identify them as regular Gammarus. (Picture 3) I also discovered some bristle worms in my tank, about 2 weeks ago. (no picture) The tank is running now for about 4 months. I started with dry rocks.


Thanks in advance,
Tschonas

 

[Mikedawg]

You might want to research gall crab. Meleev's Reef site is helpful and there are several youtube videos about removing them

 

[Tschonas]

@Mikedawg thanks for your reply, but I doupt, it is a gall crab. Don't they normally live in the polyps?

Today, I discovered another "drill hole" in an Echinophyllia. This one is struggling to survive though, but it was already not looking good since it has been in my tank. Both corals were placed in the sand.

Does any one has an other idea?

 

[Mikedawg]

Several youtube vids show them inside coral structure where they drill their hole/home