Figure 2: Scanning electron micrographs and 3D reconstructions from serial sections of erythrocyte-like structures and fibrous material.

(a, b) SEM using a backscattering detector showing cross-sections of erythrocyte-like structures c in NHMUK R12562; arrows indicate dense internal material; scale bar, 0.5 μm. (c) 3D reconstruction of serial sections of an agglomeration of erythrocyte-like structures showing: I, upwardly concave external morphology and II, dense structures observed in the interior of the erythrocyte-like structures. (d) SEM using a backscattering detector from section of fossilized bone of NHMUK R4493; arrows indicate less dense zones inside bone matrix; scale bar, 1 μm. (e) 3D reconstruction of the less dense zones in d, showing elongated, fibre-like morphology and alignment. Random colours assigned to individual fibres to differentiate between them.