The stellate holes in this Ordovician bryozoan are
not borings. They are embedment structures (referred to
as "bioclaustration", a type of bioimmuration) which
formed when a soft-bodied organism (possibly a tunicate) landed
on the living bryozoan's outer surface. The bryozoan grew up
and around the infesting animal, which at the same time developed
stolons and spread its modules laterally like strawberries. The
resulting trace fossil is called Catellocaula vallata
The scale bar is in millimeters; the specimen is from the Kope
Formation, Upper Ordovician, near Cincinnati, Ohio.
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