A lobsterpot is a trap for catching lobsters. It looks like a basket or a small cage. The fisher puts bait inside — often fish — and sinks it on the sea floor, tied to a rope and a float on the surface so the boat can find it again. A lobster can walk in after the food, but the shape of the opening makes it hard to walk out. Though actually, it is not a cooking pot: nobody boils the lobster in it. In some places people write it as two words, lobster pot. You will hear it on coasts where people fish for lobster, and in stories and pictures of that life. The same kind of trap is used for crabs; the idea is the same.