Material design for artificial reef restoration: a novel calcium carbonate biocomposite

Abstract Artificial reefs offer potential for urgent coral reef restoration, yet are frequently fabricated from materials of opportunity, without accounting for the dynamic and temporal processes necessary for a healthy reef system. We introduce a novel calcium carbonate biocomposite designed as a living artefact supporting recruitment while enabling bioerosion and recycling by reef organisms. By recognising material agentic capacity, how material properties influence organism behaviour, we consider substrate design as more-than-human design practice distinct from conventional approaches. Rather than finished objects, we reconceptualise substrates as active participants in sympoietic processes where organisms and materials mutually constitute reef ecosystems. An 8.8-month in-situ reef study shows the CaCO 3 biocomposite supported early-stage colonisation but did not yet develop communities equivalent to natural coral rubble, requiring further research and analysis of more mature benthic communities. This research demonstrates that designing with organisms as active partners, grounded in material agency, enables collaborative reef restoration practice.