Hello everyone,
these fossils are quite common in at least one Czech locality of Bohdalec formation (upper Caradoc/Beroun) and I wondered if anyone has seen anything similar somewhere. The fossils are lentil shaped, with a thin egg-like shell that could be cracked and removed to expose inner layer of different color and structure. The size is 1 to 4 mm in diameter.
I've consulted some experts and although they've all encountered similar fossil, they have no idea what it is. One of the opinions was that it could be a juvenile cystoid of some sort, for example Echinosphaerites seems to be common in this formation, although never found on this locality. However no one seems to have done any research into this yet. Associated fauna are small cyclopygid and illaenid trilobites, small brachiopods, graptolites, bivalves and ostracods.
Thanks in advance for your thoughts
Ondrej