[3] The genus Squamacula is derived from the Latin word squama, meaning scale, and the diminutive suffix -culus, indicating that the animal is relatively small.

[4] Squamacula clypeata has one pair of antennae attached to its cephalon, but no other appendages or auditory or visual structures.

The species also preserves elements of the gut tract not preserved in S. clypeata , which show that it was narrow annulated tube running along the midline of the animal, with three or possibly four pairs of midgut glands within the cephalic shield, with other gland pairs extending along the trunk.

[3] In phylogenetic analyses, Squamacula has consistently been placed as the earliest diverging and most primitive member of Artiopoda, a clade that includes trilobites and a variety of morphologically similar soft-bodied forms.

[5] Squamacula clypeata Zhiwenia coronata Australimicola spriggi Acanthomeridion serratum Acanthomeridion anacanthus Bailongia longicaudata Retifacies abnormalis Kwanyinaspis maotiashanensis Olenoides serratus Eoredlichia intermedia Haifengella corona Kuamaia lata Helmetia expansa Tegopelte gigas Skioldia aldna Saperion glumaceum Cindarella eucalla Luohuilinella deletres Luohuilinella rarus Sinoburius lunaris Xandarella spectaculum Phytophilaspis pergamena Buenaspis forteyi Tariccoia arrusensis Soomaspis splendida Liwia convexa Naraoia spinosa Naraoia compacta Misszhouia longicaudata Sidneyia inexpectans Emeraldella brocki Cheloniellon calmani Triopus draboviensis Duslia insignis Kodymirus vagans Eozetetes gemmelli Beckwithia typa Chlupacaris dubia Quasimodaspis brentsae Tremaglaspis unite Tremaglaspis vanroyi Brachyaglaspis singularis Cyclopites vulgaris Australaglaspis stonyensis Uarthrus instabilis Flobertia kochi Aglaspella granulifera Gogglops ensifer Glypharthrus simplex Aglaspis spinifer Chraspedops modesta Glypharthrus thomasi Glypharthrus trispinicaudatus Glypharthrus magnoculus A close relationship has been proposed with the genus Thulaspis from the Sirius Passet site of Greenland.