Early post-metamorphic, Carboniferous blastoid reveals the evolution and development of the digestive system in echinoderms

Early post-metamorphic, Carboniferous blastoid (NIGP 163236). (a,b,d) Scanning electron microscope images, (c,e) digital reconstructions, (f) slice image. (a) Angled upper view, (b) angled upper view, plates given false colour, (c) angled upper view, theca partly transparent, (d) lateral view, (e) lateral view, theca partly transparent and (f) transverse section. A–E, ambulacra; an, anus; bf, brachiole facets; bp, basal plate; dp, deltoid plates; fg, food groove; gl, growth lines; hd, hypodeltoid; mo, mouth; rp, radial plate; sp, stereom pores; ts, tubular structure. Colours: cyan, radial plates; green, brachiole facets; red, deltoid plates. Scale bars: 0.5 mm. (Online version in colour.)