Familiar but I don't remember what thisis

[Lance C.]

A friend likes to pick up rocks and other assorted things at estate sales. Then he brings them to me for ID. But this one is not in my areas of expertise. It seems like I've seen these for sale at rock shops, not sure. And, I'm not certain it isn't some kind of nodule or pseudo-fossil. The matrix is sandstone, with rusty iron color when scratched with fingernail. Also, because it was purchased, its natural location is unknown.

il.

[Lance C.]

I should have mentioned, it is 2-inches on its longest diameter.

[Darktooth]

It looks like a desert rose. 

[hemipristis]

Yup, desert rose, a barium sulphate nodule

[Lance C.]

Thanks! Seeing the name has refreshed my memory on this. Smaller ones are often sold with polished stones, if I recall.