My yellow polups are gone ?

[sunoka]

Something is feasting on my yellow polups. The only addition has been a Pom Pom crab and since it been added we have noticed a decline. Now my question would be is this typical of a pom pom crab to eat these.
The other tank dwellers are 1 sally light foot,1 red crown Blenny, 1 dewarf angle, couple green chromis, 1 blue line wrasse ( Dr wrasse lol ).
can anybody give some insight I`m a rookie at this only 6 mounths in .