Light (A) and scanning electron (B-I) micrographs of Nebela flabellulum. (A-E) View of different specimens to illustrate variability in shape and size of the shell. (F) Apertural view. (G) Close up view of aperture showing aperture outline and collar of organic cement. (H) Broad lateral view of apertural region. (I) Detail of shell surface showing shape and arrangement of shell-plates.