Individually these platelets are small and brittle – at half a thousandth of a milllimetre in thickness, they are close to the wavelength of visible light, leading to nacre’s distinct iridescent appearance. However collectively, the interlocking platelets embedded in their elastic mortar lend nacre high strength and cohesion, while inhibiting the propagation of cracks.

“This is interesting for space in terms of ceramics in particular,” explains ESA materials engineer Malgorzata Holynska. “We employ ceramics to produce spacecraft parts such as heat shields, optical benches and structural parts, but they are more brittle than we would like, so we are looking into how we can improve them.”