Found in the great basin on a playa/dry lake bed. There were a bunch of these in an small area (maybe 5 or 6' across). They have holes in the middle and the white remains of a material that looks plant-based (sticks?). The covering seems to be sand that is cemented onto the core material. Reminds me a bit of barnacles or some type of worm, but I am guessing that they are/were some sort of vegetation that ended up coated in sand, somehow. One friend suggested they might be fulgurites, but I don't know that they can be this small and the core material/hole makes me think not.