The unique mechanical response of spicules of Hexactinellid sponges, notably, Euplectella aspergillum, are reviewed and related to the structure, architecture, and failure modes of those natural rigid composite materials. In particular, exceptional levels of resilience, damping capacity, and the ability to dissipate mechanical energy prior to failure have been observed, all these properties greatly exceeding those of synthetic melt-fabricated glass. How these observations can be related to the design of new structural composites that are based on glass are described.