User blog comment:Kogath/Monster Hunter 4 Ultimate for the Nintendo 3DS/@comment-5805144-20141018020029/@comment-4009941-20141020152905

The snail could just be in the water in the swamp you could never swim in. Even George could be in there considering it may be a swamp monster it turns out.

In my opinion I think the skull size thing is just from very old, large, or maybe a larger subspecies that may have been so wide spread but one day went extinct. It is also possible the guild tells hunters to leave the skulls behind so the next crab can use it since they do stuff like that. There is a lot of possible ways to explain it. but no way to confirm any other than the fact its made from real Monoblos Skull.