The « Aegis Shield » is a large hydrothermal vent endemic peltospirid known only from the Longqi (aka Dragon) hydrothermal vent field, Southwest Indian Ridge, Indian Ocean; which is a bathyal site around -2700~2800m in depth. It houses chemosynthetic endosymbiont bacteria in a much enlarged oesophageal gland, and appear to rely on these for nutrition. Interestingly both its shell and operculum are covered in a thick layer of iron oxide (i.e., rust), on the operculum especially this layer is a circular slab that can reach a thickness of 5mm. It is thus another « iron-armoured snail » like the 'scaly-foot gastropod' Chrysomallon squamiferum Chen et al., 2015. Most intriguingly however the 'scaly-foot', which it lives side-by-side with, has iron sulfide coating instead of iron oxide; it is not known why the two large peltospirids living in the same environment use different iron compunds to coat their exterior surface. Furthermore, its congener G. chessoia Chen et al., 2015 from Antarctic vents does not have such iron coating at all. The function (if any) of this coating is yet unclear, although microbial activity likely contribute to its formation. The specific epithet « aegis » refers to the renowned powerful mythical shield of Athena and Zeus from the Greek mythology; named for its great thickness and also the well-polished appearance which fits well with the description of the legendary shield which is sometimes described as « mirror-like ». The bluish-white shell is quite thin, covered by a rather thick periostracum which is in turn covered by the thick rust layer. With an average shell length of 35mm. and very large specimens reaching 44mm., it is a gigantic peltospirid only exceeded in size by C. squamiferum and G. chessoia. Although a common species in its habitat, due to the extreme difficulty in collecting specimens from hydrothermal vents, it is unfortunately a virtually unobtainable species for personal collection.

Finding Place: 2785m, Tiamat Chimney', 37°47.03"S, 49°38.97'E, Longqi hydrothermal vent field, Southwest Indian Ridge, ROV Kiel 6000 Dive 142 on-board RRS James Cook expedition JC67, 2011/xi/29, 40.2mm.