Another thing about calcium sand is that it clumps when moist. I don't know if there is a big concern about snakes ingesting sand when they stick out their tongue, but it is a big concern with bearded dragons. If ingested, the sand clumps like cement in their intestines and stomach, which can cause severe and even fatal impactions.

I've seen autopsy photos and x-rays of a BD that had calcium sand blocking up the inner works...pretty nasty stuff.