SSU rRNA secondary structure of Acanthascus dawsoni [GenBank: AF100949] (Lyssacinosida, Rossellidae). Hexactinellid-specific helical insertions within E23_1 are shown in a box. Inset: Prediction of secondary structure insertions in E23_1 within other Hexactinellida. The insertions are predicted to form two helices in Hexasterophora (Lyssacinosida + Hexactinosida), and one helix in Amphidiscophora (Semperella schulzei). *Note that Farrea occa (AF159623) represents an (in other than the displayed part) incomplete, potential pseudogene molecule.