LEGO Dark Green Mermaid Tail with White Scales (18657 / 84676)

LEGO Dark Green Mermaid Tail with White Scales has been used in at least 4 LEGO sets over the past 15 years, since it was first used in 2009. It has the design IDs 18657, 84676 which can usually be found molded into the bottom of the part.