Schematics of three of the most common variants of the classical trilaminar framework for nematode eggshells, listed in order of estimated frequency of use at this time. Red labels represent noteworthy changes from the variant to the left. Notes: (1) there are two fundamentally different structures labeled as “the Lipid-rich Layer” among variants of the trilaminar framework, both of which have been shown experimentally to be lipid-rich in tested species; (2) there are two fundamentally different structures labeled as “the vitelline layer;” (3) Variant #3 skips the primal first eggshell layer to form and considers the exogenous Uterine Layer to be #1; (4) all layers (except for the Uterine Layer) in any variant of the trilaminar model are apparently present in all mitotic-stage eggshells, but advocates of one variant do not recognize some layers labeled in other variants; and (5) the only consistencies among all these trilaminar variants are that they all claim three layers and all that we have seen place the Chitinous Layer at position #2.