Face-centered cubic (fcc) Supra-crystals and disordered assemblies of Co nanocrystals have their time-dependent reflectivity compared using time-resolved confocal microscopy. The differential reflectivity exhibits a behavior strongly dependent on mesoscopic organization, an effect associated with the collective coherent vibration of the cobalt nanocrystals in the fee superstructure. The coherent vibration is mediated by interdigitated aliphatic chains acting as nanosprings.