Unusual Pin With Tree Of Shells

Glued onto a tree of clear plastic, this pin carries 21 tiny blue shells. Belonged to my grandmother and I can only assume it was a gift from her brother who vacationed in Miami annually for many years in the 1930s and 40s. After a major effort to further identify it online, I did not find anything comparable. It measures just over 4-inches tall and two-inches wide. On the back the two-inch long pin is apparently glued on but there is no indication that a catch was ever there. The glue used to attach the pin has discolored over many years but is not visible from the front. The pin has languished in my collection for nearly 45 years. I have never worn it and would consider this pin as a collection piece.