Which animal pops out its stomach through mouth?

The hagfish is an unusual animal that has a unique defense mechanism. When it is threatened, the hagfish can pop out its stomach through its mouth and use it to entangle its attacker. The hagfish's stomach is lined with sharp teeth, which can cause significant damage to the attacker. The hagfish can also secrete a slimy substance that further entangles its attacker. This defense mechanism is very effective, and it has allowed the hagfish to survive for over 300 million years.