Lotus Effect

A lotus grows in muddy ponds, yet its leaves stay spotless. The secret is texture: the surface is covered in microscopic waxy bumps that water cannot sink into. A raindrop sits on the tips like a ball on a bed of nails, then rolls off, sweeping dirt away as it goes.

Engineers copied this trick into self-cleaning paints and glass coatings. Treated building facades shed grime in the rain, so they need far less washing. A pond plant's survival trick now keeps skyscrapers clean.