Over 90% of the intracellular volume of coral gastrodermal cells is occupied by dinoflagellates; this creates quite the osmoregulatory dilemma. How do such dual-compartmental cells osmoregulate? My Ph.D. supervisor, Dr. Ruth Gates, and I asked this question in 2007, though to date little progress has been made on this topic, likely due to the difficulties in conducting basic cellular biology with endosymbiotic organisms. To be honest, this passion project of mine has stagnated over the last few years, but I am still very interested in it and hope to be able to dedicate more time to it in the near future, perhaps using the state of the art microscopy facility of Dr. Vadim Backman at Northwestern University (in vivo, probe/label-free live cell microscopy at nano-scale resolution). After all, osmoregulation is the most expensive activity in which a cell partakes, meaning it is surely to be important in our understanding of coral health (and thereby coral diagnostics).