The story behind the shells

I have had these shell necklaces for nearly 60 years. They are Polynesian, more specifically, from the island of Tahiti, when I was 10 years old and returning from living in New Zealand, the ship docked at Tahiti, and on the port side was a young girl selling these necklaces. She dropped them round my neck, but my mother said she had no money to buy them. The girl said they were a gift as I had such blonde hair! At the time, blonde hair was a rarity on the Polynesian islands, and my hair was as yellow as a haystack! I heard the other day that the Tahitian custom is normally to give flowers on arrival and shells on departure. I am not sure if that is accurate.