Figure 9

Growth process and soft part distribution of Heterocyathus sp. B. (A,B) Early growth stage of the living part and not an extension on the upper shell side. (C–E) Living part slightly inserted in the aperture of the gastropod. (F,G) Growth edge of the orifice tube structure. (F) Tube enveloped by the soft part. (G) Growth edge 6 days after (F), with the soft part only on the outer part of the tube structure.