I’m so glad I learned that I could digest rocks as an adult. I don’t think the second part of that warning would have been enough to deter me as a kid.

oh btw there's these clay eating people all around the world.

they're eaten for various reasons, sometimes because of health benefits (de-tox) or due to lack of proper food.

Impact on health

Clay minerals have been reported to have beneficial microbiological effects, such as protecting the stomach against toxins, parasites, and pathogens.[43][44] Humans are not able to synthesize vitamin B12 (cobalamin), so geophagia may be a behavioral adaptation to obtain it from bacteria in the soil.[45] Mineral content in soils may vary by region, but many contain high levels of calcium, copper, magnesium, iron, and zinc; these minerals are critical for developing fetuses, which may explain cravings by pregnant women to chew metallic objects, soil, ice cravings. Pregnant women may also experience ice-chewing cravings or drives towards specifically cold food to trigger vasoconstricting, which increases brain oxygen levels by restricting neck veins; both cravings, soil and ice, may have familial and environmental links.

What about boulders?