University researchers go to work on an egg

The researchers, who were working with colleagues from Warwick University, found that the chicken – or at least a particular chicken protein – came first in this context. However, that protein was discovered to both come first and last.

Scientists had long known that a chicken eggshell protein called OC-17 must play some role in egg shell formation. The research teams from Sheffield and Warwick then used the UK national supercomputer in Edinburgh to try to crack the problem.

They created simulations to show how the OC-17 created a chemical "clamp" to tiny particles of calcium carbonate.

While clamped in this way, the OC-17 encourages the nanoparticles of calcium carbonate to transform into "calcite crystallites" that can continue to grow on their own – and become a shell.

But they also noticed that sometimes this chemical clamp did not work and the OC-17 just seemed to detach.

The researchers had therefore uncovered a process allowing recycling of the OC-17 protein. Effectively it acts as a catalyst, clamping on to calcium carbonate particles to start crystal formation and then dropping off when the crystal nucleus is large enough to grow on its own.

This frees up the OC-17 to promote more yet more crystallisation, facilitating the speedy – literally overnight – creation of an egg shell.

Professor John Harding, from Sheffield University's department of engineering materials, said: "Understanding how chickens make eggshells is fascinating in itself but can also give clues towards designing new materials and processes."