This is the Kirks Folly Very Rare Moonlight Mermaid with Dolphin Pendant and Pin in Antique Silver Tone. 

Moonlight Mermaid is riding on a rhinestone crystal Dolphin accompanied by an Enamel Dolphin.

This is from the original Kirks Folly Era pre-2020 where you can really see the workmanship and creativity of Kirks Folly.  This can be worn as a pin or a pendant.  The pendant has the spring clasp so you can easily add it your favorite necklace.  This is a gorgeous pin/pendant and much more than the pictures show.