Scanning electron micrographs of Caecum floridanum shells at different growth stages and operculum: A Teleoconch II to III (MORG 41.867) B Truncation region between teleoconch II and III (A) C Teleoconch II to III (IBUFRJ 18376) D–F Teleoconch IV (E–F Arrows pointing to last three to four axial ribs at anterior end) (D–FIBUFRJ 18376) G Operculum, outer surface (IBUFRJ 7408) H Operculum, inner surface (IBUFRJ 7408). Scale bars: 500 µm (A, C, E–H), 100 µm (B, I), 200 µm (D).