Shells contorted, irregular in shape, attached to hard substrate by the early whorls.« The shells of the Vermetidae are at once to be distinguished from those of the Serpulae by the presence of a spiral nuclear shell and of concave smooth interior septa; but these parts are often lost or concealed, and it is then exceedingly difficult to decide with certainty whether the shell is the production of an Annelid or of a Molluscous animal. If the shell is formed of a solid matter strongly sculptured with longitudinal grooves or scales, or of a brownish colour, it is certainly formed by a Vermetus; but if the shell is of a soft earthy matter, feebly longitudinally grooved, it is doubtful to which subkingdom it belongs. » – O. A. L. Mörch: “Review of the Vermetidae” part.1, Proceedings of the Zoological Society of London for the year 1861, London 1861, p145-146. Shells of Vermetidae « function as exploratory tubes built not only to receive a better water flow, but mainly to avoid obstacles. […] This strategy allows them to compete for a virtual space, not directly occupied by the vermetid itself but necessary to spread its mucous net. » – Schiaparelli & Cattaneo-Vietti: “Functional morphology of vermetid feeding-tubes”, Lethaia vol.32(1), 1999.
 

Body whorls brownish inside. « Distinctive rnorphological characteristics for this genus are planorboid early whorls that become more loosely coiled in later stages; and the sculpture of lamellar growth striations that may or may not be intersected by longitudinal lines, sinuous and rising toward a crest near the outer edge of the whorl in most species. The operculum is well developed and equal in diameter to the aperture. » – Pacheco & Laudien: “Dendropoma mejillonensis sp. nov., a New Species of Vermetid (Caenogastropoda) from Northern Chile”, The veliger vol.50(3), Berkeley 2008, p.219.
 

« Shell tubular, solid, irregularly twisted, with two internal longitudinal plates. » – H. C. Lea: “Descriptions of Some New Fossil Shells, from the Tertiary of Petersburg, Virginia”, Transactions of the American Philosophical Society new ser., vol.IX, part.9, Philadelphia 1846, p.7. But laurae is devoid of such keels.
 

« Shell yellowish-white, loosely coiled, and usually gathering; surface spirally ribbed, covered with scales […] often obsolete near the aperture. » – P. P. Carpenter: “Monograph of the shells collected by T. Nuttall, Esq., on the California coast, in the years 1834-5”, Proceedings of the Zoological Society of London vol.XXIV, London 1856, p.226.
 

« Mörch proposed the name in a postscript to his first paper, as follows: “Enfin, je proposerai le nom de Thylaeodus pour les Vermets sans plis.” As it stands, this seems too vague to be a valid proposal, but careful reading of the paper, especially page 39, shows that he would include these species in the category of vermetids without folds […]. One may suspect that the spelling “Thylaeodus” was a printer’s error, for in the subsequent paper, where more formal treatment was given, the spelling was consistently “Thylacodus”. However, under the International Rules, the original spelling must be accepted unless evidence in the paper itself demonstrates an error. Mörch having given no clue as to derivation, we must adopt Thylaeodus as the valid spelling. In a way this is advantageous, for thus we avoid the confusion of Thylacodus with Thylacodes, names used by Mörch in different senses. » – A. M. Keen: “A proposed reclassification of the gastropod family Vermetidae”, Bulletin of the British Museum vol.VII, London 1961, p.192. Later, Keen specifies (p.193): « Buff to brown shells of moderate or small diameter, with strongly cancellate to beaded sculpture; feeding-tube scars (abandoned remnants of former vertical tubes) present on most specimens; operculum one-half to three-fourths the diameter of the aperture, with a spiral lamina of chitin that rises free from the disc. »
 

« Mainly solitary or in small clusters, coiling usually irregular; columellar wall smooth, without laminae; nuclear whorls two, globose to elongate; operculum thin, spiral, one-half or less the diameter of the aperture. […] shell mostly well attached; without feeding-tube scars… » – A. M. Keen: “A proposed reclassification of the gastropod family Vermetidae”, Bulletin of the British Museum vol.VII, London 1961, p.193.