A well-known example is nacre, which is used in jewellery because of its iridescent colours.

The mollusc deposits layers of aragonite and conchiolin, which together form nacre, also know as mother-of-pearl.

Dull on the outside, its nacre gleams pearlescent within.

Natural materials such as bone, silk and nacre have exceptional properties that many conventional engineering materials lack.

A delicate thread of continuity connects these flashes of story, each complete and perfect in and of itself but accreting meaning like nacre on a pearl.