what have happened to my digi ? please help

[chercm]

any idea what happened ?

there is no crab in my tank

 

[Bandos reefer]

Any chance of a clearer shot?

 

[chercm]

here are the picx

 

[SneekaPeek]

blow it off, could be debris in coralites.

 

[chercm]

If it is bitten by crabs will it recover ?