I was served these in the reverse order, followed by this comment and almost lost it 😂

I feel like using quartz as a gastrolith would be pretty basic, like you might as well eat those silica packets or chew on some glass if you're going that direction. Some nice gneiss would likely be preferable, much more cultured at least.

Yup, OP text writer has no idea what they're talking about. The organisms that make this sand still exist today and are still making this sand

https://www.nationalgeographic.com/science/article/okinawa-japan-star-sand

Probably like the sand that looks loke amazing snowflakes. The image for that one used selected granules from thousands (billions). Most sand is just ugly, and micro plastics.

Oh my god I forgot about those. I unironically loved them.

Perfection. 10/10, would listen.

Edit to add: Damn, now I really want an Okinawa Boneyard band t-shirt.

I love that one - it's on their Christmas album!