High-resolution imaging sheds new light on a multi-tier symbiotic partnership between a "walking" solitary coral, a sipunculan, and a bivalve from East Africa.

Marine symbioses are integral to the persistence of ecosystem functioning in coral reefs. Solitary corals of the species and have been observed to live in symbiosis with the sipunculan worm , which inhabits a cavity within the coral, in Zanzibar (Tanzania). The symbiosis of these photosymbiotic corals enables the coral holobiont to move, in fine to coarse unconsolidated substrata, a process termed as "walking.