Stalked barnacles represent an evolutionarily earlier lineage than acorn barnacles. They not only rely on rigid shell plates but also a unique flexible yet protective stalk to withstand powerful and repeated wave-induced mechanical forces in intertidal environments. However, their mechanical properties remain poorly understood. In this study, the gooseneck barnacle (Capitulum mitella) was investigated by the Materials Science approaches. Its hierarchical structure and elemental composition were characterized using PXM, SEM, EPMA, XRD, and FTIR. Tensile testing and nanoindentation were further conducted to evaluate its mechanical performance. The results revealed pronounced tensile anisotropy in the stalk, with transverse tensile specimens exhibiting approximately 1.9 times higher elastic modulus and ultimate tensile stress than longitudinal specimens, accompanied by distinct crack propagation and fracture behaviors. Notably, this study provided the first systematic evidence of soft-hard material integration within the scales, which were embedded on the stalk. Nanoindentation results indicated that the mineralized core exhibits a hardness more than an order of magnitude higher than that of the surrounding non-mineralized region, despite the absence of a distinct graded transition layer. This sharp mechanical contrast suggested a direct soft–hard integration strategy, in which the compliant organic outer layer contributes to energy dissipation and mitigates stress concentration in the stiff mineralized core. This work elucidated the hierarchical structure and mechanical adaptation mechanisms of C. mitella, which offered new insights for bio-inspired protective armor design.