Bryozoan or Coral ?
St. Louis County, Missouri
Interesting little "bell" shapes
It may belong among the enigmatic Hederelloidea, which have commonly in
the past been included in the Cyclostomata but which have different skeletal
microstructure and "zooecia" that are probably a bit too big to be bryozoans.
(In my master's thesis back in the late 1960s, I accepted hederelloids as bryozoans
but have long since changed my mind.)
I think possibly it could be an auloporid coral, but equally or more likely it is
a hederelloid, given its golden color compared with the gray color of the fenestrate
bryozoan adjacent to it.
Dr. Frank K. (Ken) McKinney
This appears to be an undescribed fossil, so let's be cautious about trying to identify it.
The comments from Ken McKinney seem to be on the mark. The chambers are larger
than the chambers housing zooids of known bryozoans, but are the same size as those
of an auloporid coral. This is an important character for determining affinity or choosing
between coral and bryozoan. The chamber arrangement is unique, unlike any reported
auloporid coral or reported bryozoan, but chamber arrangement can be easily modified
by colonial organisms like the corals (or bryozoans).
Summary: They show more similarity to corals than bryozoans.
This illustration of this fossil shows that discoveries of new
fossils can be made by anyone.
Dr. Tom Yancey
Mississippian Fossils of Missouri