Gavish et al. used time-lapsed microscopy and a microfluidics set-up to track infection of the stony coral Pocillopora damicornis with Vibrio coralliilyticus, a bacterial pathogen known to contribute to coral disease, in particular under warming conditions. The authors incubated 5 mm big pieces of coral and inoculated them with a high load of V. coralliilyticus. The coral and the algal symbionts are autofluorescent, whereas the bacteria were transformed with a red fluorescent marker. Bacteria entered the coral polyp through the mouth, infecting the pharynx, or through pre-existing surface lesions. Shortly after infection, the corals retracted the polyps and ‘spewed’ bacteria-laden mucus, presumably to lower pathogen loads. About one-third of polyps could prevent disease in this way and subsequently remained asymptomatic. By contrast, symptomatic corals showed extensive tissue necrosis and loss of colony integrity. However, most symptomatic corals showed at least partial survival of the polyps and some polyps ‘bailed out’, separating from the skeleton and remaining viable, thus potentially able to establish new colonies.