Rust: An indicator of time

This pipe just outside of my dorm has heavily rusted as it has aged. Rusting is a way for nature to indicate that time has passed – when we see it, we immediately associate it with age and “old.” Unlike the cycles of leaves changing color or rings in a tree trunk, it doesn’t really have cycles. It is quite mysterious, since the rust forms depending on many variables in the environment it endured. It is an obvious indicator that time has passed, but doesn’t tell us much else.