Spore clots in Rhynie chert
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Aglaophyton sporangium detail
Mature spores as in Fig.1 are released from the sporangia as loose grains, as expected. So it is surprising that spores are not seldom seen in globular lumps (Figs.2-6).

Fig.1 (right): Detail of Aglaophyton sporangium: wall with so-called palisade cells (left), sporogenic tissue, spores. Width of the picture 1.7mm.
AgAg 0.8mm
Figs.2,3: Aglaophyton spores, separate and in globular clots. Height of the pictures 0.8mm. All pictures of same scale.
Aglaophyton spore clot Aglaophyton spore clot
Fig.4 (far left): Aglaophyton spores in a globular clot.
Width of the picture 1.4mm.

Fig.5 (left): Aglaophyton spores in a globular clot, apparently partially chewed up.
Width of the picture 1.4mm.

Aglaophyton spore clot

Fig.6 (right): Aglaophyton spores in a globular clot, with mineral debris apparently glued to the surface.
(One circular spore contour is faintly seen above left.) Width of the picture 1.4mm.

The peculiar clots shown here require an explanation. The statement in [1] that "evidence for deliberately targeted spore feeding in the Early Devonian is not conclusive" had been contradicted by own observations in 2005: There were spore eaters around when the early land plants became preserved in the Rhynie chert. This has suggested a phantastic idea: Possibly some creature collected the scattered spores and glued them into spheres for transport, storage, and later use as food. A few spores nibbled off the surface of the clot in Fig.5 seems to support this assumption. The mineral debris sticking to the clot in Fig.6 supports the idea of glueing.
Unrelated to the clot problem but worth mentioning are lots of tiny black dots in Fig.6, probably microbes stuck to a former silica gel surface.
Annotation 2021: An uninspired explanation for the existence of spore clots is offered in [2]: "Clusters of spores or spore balls are typically found in the chert matrix, suggesting that the spores may have been shed en masse (Fig.8.31)." (The scale bar in that figure should be rather 0.1mm than 1mm.)
A sphere with a thousand spores like the one in Fig.3 cannot simply result from shedding. Also it cannot have been formed inside the sporangium since mature Aglaophyton sporangia are known to split open with a longitudinal fissure too narrow for clots. 
Rh9/93 (0.55kg), found by S. Weiss in 2011, cut into 10 parts, Part5: Fig.1.

Rh2/4, obtained from Shanks in 1998, cut into 4 parts, Part2 returned. Part1 (slab, given to J. Gardavsky): Figs.5,6; Part3 (slab, in the own collection): Fig.2,4.
Rh4/22 (1.3kg), found by S. Weiss in 2000, cut into 2 parts, Part2: Fig.3.

H.-J. Weiss       2019,  2021

[1]  K.S. Habgood, H. Hass, H. Kerp: Evidence for an early terrestrial food web: coprolites from the Early Devonian Rhynie chert.
        Proc. Roy. Soc. Edinburgh, Earth Sci. 94 (2004), 371-389.

[2]  T.N. Taylor, E.L. Taylor, M. Krings: Paleobotany, Elsevier 2009, Fig.8.31.
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