The problem was never the fabric. It was the damp.
Every fabric bath mat has the same flaw: it holds water. It stays wet for hours, grows that familiar smell no wash cycle quite removes, and ends up in the laundry basket every week. Memory foam, cotton, microfiber — the material changes, the problem doesn't.
So we started from the water instead of the fabric. Diatomaceous earth — the fossilized remains of freshwater algae — is riddled with microscopic pores that pull water off the surface in seconds and let it evaporate in minutes. Shape it into a slab, give it a non-slip base, and the bath mat stops being a chore.