Nanoindentation probing on nacre obtained from Haliotis rufescens shells has demonstrated that nacre displays a combined viscoplastic-viscoelastic time dependent response. Additionally, it is found that the moisture/water content of nacre contributes to its time dependent behavior and overall mechanical properties. Detailed finite element simulations allow for the determination of constitutive parameters used to calibrate specific time dependent material models which are, in turn, compared to those found via independent measurement as reported in the literature. The results lead to a new paradigm for nacre’s attractive structural composite behavior and thereby to new potential pathways for biomimetics.