(A) Optical microscopy of a cross-section through the shell of Eoconus edwardsi (BR1) with magnification 39x, showing well-preserved cross-laminar and prismatic aragonite crystals. (B) Cathodoluminescence microscopy of an internal cross-section through Eoconus deperditus (FL2), showing a faint dark blue luminescence indicative of preserved aragonite. (C, D) SEM microscopy of the cross-laminar aragonite crystals of Eoconus edwardsi (C), and Eoconus deperditus (D).