[TeMPOraL]

I view stuff like lead less as something that biosphere couldn't figure out how to recycle yet, so it sequesters and buries it - but by the nature of how life works, if some random mutation would make lead useful as a building block (like many, many other elements are), the biosphere would happily suck all the lead back up and spread it.

The pattern I see here is that over time, the biosphere makes everything it finds useful diffuse, present everywhere in low concentrations; everything else, it sequesters and stashes in high concentration in few places. So not unlike what our industry is doing, just with different materials.