I created a super class that extends EntityCreature. It is a class that contains the things I want all the subclasses to have. Then, I created a basic subclass and registered it as a wither skeleton, but in game, it is an invisible thing (I have never seen it, I just see particles when I spawn it and it hits the ground). Is this because I registered a EntityCreature as a wither skeleton? If so, how would I create a super class that splits off into other creature types?