Mussel Glue Underwater

A mussel clings to a wave-pounded rock with byssal threads, tough fibers it grows and tips with a natural glue. The glue's secret ingredient is an amino acid called DOPA, which bonds to surfaces even when they are soaking wet.

That is backwards from how human glues behave. Most fail the moment water gets between them and the surface. Mussel glue does the opposite: it sets better wet than dry.