Description of Nebelidae

Shell composed of shell plates of small euglyphids (e.g. Euglypha, Trinema, Tracheleuglypha), or plates of Quadrulella and diatom fragments. The assumption in the older literature that the Nebelidae can synthesize their own siliceous ideosoms has not been proven. There is some evidence from scanning electron microscopy that members of the genus Argynnia can coat foreign building material. Usually Nebelidae fix the building material in a sheet-like organic cement matrix, which is normally visible between the plates, only Argynnia and Physochila use distinct cement units. When building materials are limited the test of some species are completely organic (e.g. N. tincta, A. cockayni).