Help Me Catch The Thief!

[MarkoD]

ok so one of my fish is being sneaky and picking up large frags and hiding them somewhere......

i bought a purple haze montipora frag yesterday. about 1.5 inches encrusted to a small rock, i wedged it into my live rock and made sure it was secure.

looks like one of my fish moved it and hid it somewhere. its nowhere to be found and its definatly to heavy to be blown away by the current. (its not like it fell off the rock into the sand, its literally gone and somewhere in the rockwork)

anyone know which one of my fish it could be?
I have:

about 6-7" regal tang
two 4" yellow tangs
5" foxface
two 1.5" clarkii clowns
2" coral beauty
2" cleaner wrasse
4" fairy wrasse
2" mandarin goby