Tower Shell

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These big seven and a half feet tall of walking seashells are called Tower Shells. The prominent thing to know about this creature is that it is always carrying another type of creature on its back called a Muret. While it isn't known when this pairing started or when it occurs (possibly birth), for each Tower Shell there is always a Muret on its back.
The Tower Shell is fairly slow when it comes to movement, but its defensive properties aren't to be taken lightly. It will do everything in its power to protect the Muret on its back. The reason why it is so protective is because the Muret provides the Tower Shell with food. It is the one killing and doing the hunting (so to speak), while the Tower Shell provides protection from other creatures and the environment.
Thankfully the pair of creatures aren't too often seen by people, and they tend to stay away from humanoid settlements, decidedly staying in the oceans or lakes. It only occasionally comes out to hunt prey if the water doesn't prove fruitful for food.