Light (A) and scanning electron (B-I) micrographs of Trinema enchelys. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C, D) Apertural view of two specimens showing general shape and regular arrangement of shell-plates. (E) Dorsal view. (F) Lateral view. (G) Close up view of apertural region. (H) Close up view of denticulate apertural-plates. (I) Detail of shell surface to show large, circular shell-plates and small, oval shell-plates which haphazardly fill the interstices between them.