What are three examples of nonliving things that were once living things?

Answer 1

Things like, obviously fossils, but if you dive deeper, you can say things like petroleum is made of fossils, which were once living and even things like the dirt we stand on is partially made of decomposed plants and various materials. But, by the question your asking a dead person would also be an answer.

Answer 2

1. Fossil fuels (coal, oil, natural gas) are derived from once-living plants and animals.
2. Wooden furniture is made from trees that were once alive.
3. Leather products are derived from animal hides that were once part of living animals.