To early malacologists who subsisted on a diet of oriental exotica, these snails must have recalled the conical headgear of far eastern peasants. To present-day observers, Bicatillus extinctorium more closely resembles glossy deposits of cocoa mass and butter extruded from miniature nozzles, each calibrated to produce a perfect drop of confection with a generous base and gentle spire. Others have termed this molluscs cup-and-saucer limpets, on account of their interior sculpture, which consists of a smooth concavity disrupted by an appendage variously compared to a tongue, cup, horn or horseshoe. How this process, which also occurs in Calyptraea and Crucibulum (genera to which extinctorium was formerly assigned) and is probably a relict of ancient coils that serves as an anchor for the softer parts of the animal, evoked visions of fine china beggars the imagination, but it seems unlikely that these little snails will be able to shake off their oriental monikers, even in this age of post-colonial acrimony.
The morbid epithet of this gastropod, which is a limpet only in sensu lato, may have arose from the discovery of fossil remains prior to encounters with extant specimens. Locally, the snails once thrived on small rocks "along the low water mark" of an artificial bay fed by the Singapore River, a habitat that has since been sundered from the sea. Flushed from their former haunts, the limpets now survive in eastern refuges, in the seagrass beds off Changi Point, the flats of Chek Jawa and a sandy expanse just beyond a reclaimed shore. Here, on the valves of a clam that floats on soft mud and loose sediments, cling a brace of hats, one of which served as a mount for a dwarfish mate. Like their placunid vehicle, the calyptraeids are respectable filter feeders with little hunger for adventure, who subsist on a planktonic soup, which they ram through their gills before slurping the enmeshed cells via a string of mucus. Pioneers who prosper probably emit chemical signatures that draw other veligers, who arrive as studs, latching on to former lads and launching amourous protuberances into willing mantles until they too slip into submission to biological clocks that force each suitor to assume a new position as consort to a younger lord.