The importance of the thin helicoidal region for the overall damage behavior of the spike is further demonstrated using multimaterial 3D printing (Figure 7 ). We designed spike-inspired multilayered samples with and without a thin twisted plywood (mimicking the outer helicoidal region) sandwiched between a stiff monolithic but brittle outer region (mimicking the highly mineralized region) and a more compliant but anisotropic parallel-fiber region (mimicking the striated region). We used cuboid samples and performed macroscopic penetration tests at high strain rate using a blunt tip (Figure 7A). Notched samples were tested in 3-point-bending up to fracture (Figure 7B). The twisted plywood region connecting the still/brittle with the compliant/anisotropic region has a strong impact on the strength, energy absorption and failure characteristics of the spike-inspired system in both scenarios. Considering penetration tests, force-displacement curves show two peaks (Figure 7A): the first one happening just before the breaking of the stiff outer layer and the second due to damage propagating within the underlying fibrous and more compliant region (Figure 7C). Interestingly, the presence of the plywood not only increases the force needed to propagate the damage in the softer region (by 40%) but also the force necessary to break the stiff layer (by 25%). At the same time, it has no influence on the contact stiffness, as indicated by the same initial slope of the curves. Concerning the 3-point-bending tests (Figure 7B), in the sample without twisted plywood, a main crack nucleates from the notch (Figure 7D-I) and propagates straight in the parallel fibers region with only minimal delamination (Figure 7D-II). As soon as the crack meets the stiff outer region, a catastrophic failure is observed and the broken sample “splashes away” from the supports (Figure 7D-III). In the second scenario, the crack also starts from the notch within the parallel fibers region (Figure 7D-pI) and propagates straight (Figure 7D-pII) up to the helicoidal region. There, the main crack branches symmetrically into two smaller cracks which propagate horizontally, causing delamination. A similar pattern is repeated one more time, while the crack advances in the helicoidal plywood region (Figure 7D-pIII). Such crack branching and delamination are important toughening mechanisms which delay catastrophic failure, increasing by almost 50 % the energy absorption of the synthetic sample. Interpreting this behavior in the context of the spike may suggest that, that although HMR and STR are well-suited to reinforce the spike under contact forces (HMR) and axial loading (STR), the combination of these two regions is not efficiently dealing with damage propagation. The thin plywood region is therefore required to fulfill this task.