Previously I had a question about desecrating Jewish gravestones, but now I would have one in the opposite direction. In Christian cemeteries it's fairly common to dismantle graves after a few decades and put the remains in ossuaries. Often being constructed of expensive materials, these tombstones are frequently sold and re-used. I'm also aware of an ancient Roman stele that was eventually re-used by Jews. What does Jewish sources say about this practice? Can Jews use such materials? Should we be concerned with possible idol worship?