The red decorator crab (Schizophrys aspera; Majidae) resides in coral rubble and is a successful predator of juvenile Crown-of-Thorns starfish (CoTS; Acanthaster sp.). However, little is known about Schizophrys on the Great Barrier Reef, including their biology, and decorating processes. We characterised S. aspera and their epibiont communities from rubble patches of Heron Island on the southern Great Barrier Reef. The mean carapace size was ~25 mm with a population skewed towards females. The epibiont community was dominated by sponges, which differs from reports of Schizophrys spp. elsewhere that tend to have a higher composition of barnacles, polychaetes, and tunicates. There was no relationship between the proportion of epibionts with carapace size or sex. Tank experiments showed the uptake of sessile taxa was rapid post-moult with measurable epibiont growth within days. We postulate the close association of S. aspera with Porifera enhances camouflage and chemical defences and may also confer resilience to plancitoxins associated with CoTS.