Fig. 5

Selkirkia sinica from the early Cambrian Chengjiang Lagerstätte: protruding trunk in various length. a, b ELI-0002005, general view, and close-up (trunk protruding about 1 mm outside tube opening). c, d ELI-0002006, general view, and close-up (trunk protruding about 2 mm outside tube opening). e, f ELI-0002007, protruding trunk and distinct gap between trunk and tube (black line), and mineral grains (white arrow). g–i ELI-0002008, general view, and close-up (trunk protruding about 3 mm outside tube opening). h and i represent part and counterpart, respectively. j–l ELI-0002009, general view, and close-up (trunk protruding about 7 mm outside tube opening). m–n ELI-0002010, general view, and close-up (trunk protruding about 3 mm outside tube opening). o–p ELI-0002011, general view, and line drawing (trunk protruding about 10 mm beyond tube opening, almost equivalent to tube length). Black arrows indicate the trunk cuticle, white double arrows indicate the protruding length of the trunk. I, II and III represent Zone I, Zone II and Zone III, respectively. Ia, Ib and Ic represent the subdivisions of Zone I. Green lines and grey area in p indicate the gut and inner surface of the tube, respectively. Scale bars represent a, c, g, j, m and o 5 mm; e 2 mm; b, d, f, h, i, k, l and n 1 mm