The Mermaids are mythical sea creatures from Welcome To The Bikini Bottom Triangle. It appears that there are 5 mermaids like Mindy (King Neptune's Daughter). They first appeared as antagonists, as they stole many objects from Bikini Bottom. 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. 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.
This might bee a copy-cat of a book from a series called Fairy Realm, in which things thaFile:Mall.jpgt look like mermaids steal stuff, and like singing a song, they use a flute to get it.
They resemble King Triton's daughters from the Little Mermaid all except instead of 7 there are 5.