Octopants and the Missing Pirate Underpants

Puffer Fish wakes up one morning to find that his pirate underwear has been taken from the clothesline So Octopants the octopus offers to help look for them. They check Lobster's Laundry, look through Mermaid's hair, and even stop by Mussel's Fitness Club, but the underwear isn't anywhere. They even find a shipwreck that's full of underwear collected by friendly pirates, but there's still no sign of Puffer Fish's underwear. Then Shark appears and wants to join the group. But what's that on her head?