help what is this on my live rock

[fire0700]

tanks doing great. peppermint shrimp alive and well. mantis seems happy with them. I injected the large one with lemon juice twice and its gone also.

 

[clownfitch]

The mantis didnt munch the peppermints??

 

[fire0700]

No. It appeared the mantis avoided them. They did however flip the turbo snails over and ate all of them. And I'm pretty certain that they ate some coral and pineapple sponges. I gave all 4 of them to Petco.