A particular connection
of alga tubes
What looks like a special connection of tubes in this sample
of Rhynie chert seems
to be a severely deformed contact site between
the adhering tube-like cells of the charophyte alga Palaeonitella.
Image: Seldom seen phenomenon of uncommon contact
area of what seems to
be adhering tube-like charophyte alga cells. Image width 1.5mm.
With the conspicuous pairs of
spheres in mind, which are occasionally
seen in the chert, the idea suggests
itself that the bloated ends of the adjacent cells seen here could
have been an early stage of the formation of spheres in pairs.
It is known that Palaeonitella
can grow spherically bloated cells
under the influence of some parasitic fungus
The fact that the structure shown here is extremely rare while big
spheres in pairs may be seen by the dozen in one chert sample leads to
the tentative conclusion that it is a short-lived transient stage while
spheres are persistent by design. This would be compatible with the
observation that the pairs of spheres are often seen without any
attached alga since the alga could
have decayed before silicification while the spheres persisted. Also it
would favour the interpretation of spheres in pairs as alga formations
but not as fungus chlamydospores.
It must be admitted that the conclusions derived here from this one and
only formation of this type may be not quite convincing. Other
suggestions for an explanation would be welcome.
taken from a sample in
the collection of Steffen
collected decades ago by
formerly owned by A.G.
Rhynie, documented here under the label Rh2/303.1 .
 T.N.Taylor, M. Krings, E.L. Taylor: Fossil
Fungi. Elsevier 2015, p.64.