Probing nonequilibrium mechanical response of living chiral crystals

Developing starfish embryos can form living chiral crystals (LCC). Individual embryos swim, rotate, and interact non-reciprocally with each other. Broken time reversal symmetry leads to emergence of a variety of rich phenomena in this system, including chiral displacement waves. We investigate the interplay between nonequilibrium thermodynamics and mechanics, by applying frequency-dependent mechanical perturbations on LCCs. Interestingly, displacement waves can be excited by mechanical perturbation of LCC, and disturbed crystalline order can be restored. Our results can have potential implications for design and development of metamaterials.