The cage is the latest membership item, it stores animals. Hate helped me collect some rabbits and bees (he's the oldest player in the game, used to rule the land but now he gets killed all the time).
I tried trapping them on the roof, but I forgot rabbits can jump:
I suppose there is some theoretical gameplay use, since bees might absorb blows from monsters or even players. But it is mainly fun to release animals in obscure places. If the game has distant exotic lands someday then the cage could be used to bring back rare animals. I put some bees in Gurun's shop which might have surprised people: