In Season 3, the girls find some matching necklaces, that  in a way, match them. Amy finds a blue one while swimming, so it matches her tail, and how power/element, water. Brenna finds a yellow-orange one in the fire pit, so it matches her tail color, and her power/element, fire. Kelsey finds one that is purple, which is strange, because she is the only one that does not have her's match her power/element, or tail. It is especially strange, because even Terra has one that matches her element and tail, seeing as the girls figure out that her element has to do with earth. Terra's necklace is green, but she left it with all of her things that she left behind on land, this is how she was able to send a siren to Blaire (She had been wearing her mom's necklace).