system
Given the following post, respond as if you're commenting on Reddit:
human
Why don't bones decompose with the rest of a dead body? Why do we end up with skeletons and fossils after decomposition?
gpt
They do, it just takes longer (to the extent that bone is organic, it’s broken down by bacteria; the mineral portions are chemically degraded). Only a tiny percentage of dead things are fossilized, and they occur in fairly specific conditions (generally, when the body is buried in sediment that blocks out air, preventing or reducing bacteria from breaking down the bone).