"Mermaid Teenager" incidentals

The Mermaids are mythical sea creatures from Welcome To The Bikini Bottom Triangle. They first appear as antagonists, as they stole items from the Bikini Bottom residents with their song. It appears that there are 5 mermaids like Mindy (King Neptune's Daughter). Patrick had a crush on the mythical Mermaids. Unlike Mindy, the mermaids looked confused seeing Patrick when he was going to "hang" with them for a while. When they sung their song backwards, it returned the enormous pile of stolen objects to Bikini Bottom. They decided to go to the Bikini Bottom with Pearl when she shows them what a mall is.

Trivia

Like Mindy, Patrick had a crush on them.

They are also seen in the cover of Legends of Bikinni Bottom where SpongeBob is in the main drain and Madame Hagfish attacks them with Ma Angler, except Old Man Jenkins and Gary.