it is kinda hard to tell from your pix but i find those every day on my beach. the ones i find are clay and are either fossil impressions of sand shrimp burrows or accumulations around 80,000 year old roots and twigs. is the one you found able to be "scratched" easily? if so, it is probably natural.
my elderly mom in Florida gave me a whistle made of clay shaped like a bird. The item was from mexico.
could be the same sort of item.
It was suggested that I post this here. Thought I’d post here to pick your brains.
This was found on Crystal Beach in Texas (Gulf of Mexico). Caught our eye every time the tide would go out. Thought it had an interesting shape to it so kept it.
View attachment 1692218View attachment 1692219View attachment 1692220View attachment 1692221View attachment 1692222View attachment 1692223View attachment 1692224View attachment 1692225
I believe this is what you have found. Festival whistles from Mexico, these are about forty years old.