Fig. 6

a This medium-sized Seirocrinus from the Posidonia Shale is the hoped-for Rosetta Stone, because it broke off a driftwood and sank to the bottom with the heavy stem ahead. It shows the “miniskirt” of small cylindrical cirri protecting the nodal factory. Further away from the crown, cirri (arrows) became atrophied and distanced by up to 31 internodals. Near the distal end they are again larger and crowded into a root tuft. Note that breaks happened commonly on the proximal side of a nodal. b Close-up showing that root cirri are compressed and branch-off towards the crown, as in Pentacrinites, before turning towards the substrate for a subsequent root function. The three distancing internodals, however, grew to equal thickness in the more proximal parts of the stem. (GPIT 1918/2; phot. W. Gerber)