Mushroom flathead coral parasite eating at 'foot stumps' of mushroom coral or normal pedal laceration behavior?

[KingLucy1997]

I have a few month old 3.5 ish gallon tank with one Turbo Snail, a ton of live rock from E-bay (claimed the live rock was cured) and a large mushroom coral frag. The live rock is teaming with life, so it is hard to tell the difference between what is a live rock hitchhiker and what is a tentacle/part of the mushroom coral. Today I noticed that the mushroom was trying to force its way off of its frag plug. Around the 'feet' of the mushroom (where there is calcification) I am noticing these tentacles and maybe what looks like crab claws coming out from under the coral's feet. It seems like blackness is spreading up the opposite side of the base, which appear similar to some of the hitch hikers I have seen in the live rock pores. The more I observe the the coral the more confident I am that something is eating it. The coral now appears to be starting to split apart, which could support both theories.
It really does look like a separate organism is consuming the coral to me. Unfortunately it hides from light so is very hard to photograph what is happening but I did my best.
My Turbo snail is happy and seems normal.

 

[KingLucy1997]

I dipped the mushroom but not the live rocks before adding them to the tank. I just put in the extra live rock from Ebay and mushroom coral yesterday.

 

[Goaway]

If you are suspecting a crab eating the coral (which they do) try to use some shrimp to lure the critter out. You wont be able to catch him. But it will help you confirm it's a crab. If it is enjoying the leather as a meal too much, it may not come out of hiding.

 

[Goaway]

It doesn't need to be shrimp either, can be clam, muscle, squid. Some form of raw stinky sea food.

 

[KingLucy1997]

If you are suspecting a crab eating the coral (which they do) try to use some shrimp to lure the critter out. You wont be able to catch him. But it will help you confirm it's a crab. If it is enjoying the leather as a meal too much, it may not come out of hiding.

It does kind of look like a crab from the few glimpses I got. Even if it is a crab could it be a parasitic one for corals or will he be beneficial once he learns how to eat other things?

 

[Goaway]

You would have to remove the coral and inspect for injury. Only 1 crab I know of is rather reef safe. Those are the porcelain crabs. Since they are filter feeders. If the crab is already munching on the coral, that's what it will do as long as the coral is there.

 

[KingLucy1997]

You would have to remove the coral and inspect for injury. Only 1 crab I know of is rather reef safe. Those are the porcelain crabs. Since they are filter feeders. If the crab is already munching on the coral, that's what it will do as long as the coral is there.

So I have to pick between the crab and the coral?

 

[Goaway]

Pretty much, you won't get to see the crab too often.

 

[KingLucy1997]

Pretty much, you won't get to see the crab too often.

It’s definitely a crustacean. Body plan is crab like, seems to have a twig thin body and almost a cobra or Shield shaped head. He likes dried seaweed because it quit chewing on my coral for a few seconds. My glass is shaped weird so it’s hard to tell if a rock is being moved by the crab, it’s part of its shell or is an entirely different organism

 

[Saltyreef]

Looks like a toadstool leather (sometimes refered to as a toadstool mushroom)
Different than Corallimorpharia.

They don't propigate by pedal lasceration but rather drop pieces of their caps.

 

[Goaway]

It’s definitely a crustacean. Body plan is crab like, seems to have a twig thin body and almost a cobra or Shield shaped head. He likes dried seaweed because it quit chewing on my coral for a few seconds. My glass is shaped weird so it’s hard to tell if a rock is being moved by the crab, it’s part of its shell or is an entirely different organism

Does it look like this? Also, can you give me a full picture of the aquarium it is in?

 

[KingLucy1997]

Does it look like this? Also, can you give me a full picture of the aquarium it is in?

Do they stand upright? It was hard to see because I was feeding, limbs didn't really seem connected to the head, or at least not to the large shield like head structure. It had two equally sized primary claw limbs just below its ‘shield head’ and the rest of the limbs appeared to be attached to some kind of thin body below the shield head. Ill try to get a picture.

 

[KingLucy1997]

Do they stand upright? It was hard to see because I was feeding, limbs didn't really seem connected to the head, or at least not to the large shield like head structure. It had two equally sized primary claw limbs just below its ‘shield head’ and the rest of the limbs appeared to be attached to some kind of thin body below the shield head. Ill try to get a picture.

Still have only been able to get glimpses of the crab thing because it is very light adverse

 

[KingLucy1997]

Does it look like this? Also, can you give me a full picture of the aquarium it is in?

The crab behaves as if it’s a tuxedo urchin. It is camaflouging itself with bits of rock and seaweed. Smart little fella

 

[KingLucy1997]

Does it look like this? Also, can you give me a full picture of the aquarium it is in?

Honestly I the coral doesn’t even look that damaged and is large enough to seem like it’s able to replenish with growth what it lost from the crab. It’s the only coral in there besides some red Zoa like polyps that started popping up after I added the new live rock. There isn’t even room to add more things to the tank even if I wanted to. The crab might be able to do the pruning of that leather coral for me, as long as it doesn’t turn into a gorilla sized crab!

 

[Goaway]

If you don't mind the crab, it's fine. Sally will get much bigger though, eventually run out of a hiding spot. It probably is a sally lightfoot. I would drop it some food once in awhile if you're going to keep it. Which is mostly nori/seaweed. Softer algaes.

I really couldn't make anything out other than the chaeto.

 

[KingLucy1997]

If you don't mind the crab, it's fine. Sally will get much bigger though, eventually run out of a hiding spot. It probably is a sally lightfoot. I would drop it some food once in awhile if you're going to keep it. Which is mostly nori/seaweed. Softer algaes.

I really couldn't make anything out other than the chaeto.

Are Sally’s known to use camouflage like tuxedo urchins?

 

[KingLucy1997]

Are Sally’s known to use camouflage like tuxedo urchins?

Honestly I think it is a decorator crab based on its behavior of covering itself with different bits and bobs. Apparently you rarely see a decorator crab’s body because it covers itself with other stuff in the aquarium

 

[Goaway]

Honestly I think it is a decorator crab based on its behavior of covering itself with different bits and bobs. Apparently you rarely see a decorator crab’s body because it covers itself with other stuff in the aquarium

I can't make any of it out. It could be a decorator crab. If it ever comes out of hiding, just snap a pic. If nothing looks bad. Don't worry about him.

 

[KingLucy1997]

I can't make any of it out. It could be a decorator crab. If it ever comes out of hiding, just snap a pic. If nothing looks bad. Don't worry about him.

You can’t see anything in the pictures because he is a good decorator crab! I can only tell he’s there when he is moving. I can only see crab legs and sort of eye stalks sometimes but can see a mass of random things moving around like something is under them that would only be noticeable in a video. Thanks for you help!