POV: you went diving at night and spotted Ordovician nautiloids feasting on a eurypterid carcass, after a while the commotion has attracted the giants, Endoceratids slowly creeping into view
Trilobites were marine arthropods that inhabited the oceans from the Cambrian (521 Ma) to the Permian (251 Ma). They display beautiful calcitic exoskeletons that are often ornamented of genal, thoracic and pygidial spines. Trilobites were also the first group of animals to develop complex eyes that are sometimes incredibly well-preserved. The fine trilobites here offered for sale were carefully selected by us. Our criteria include rarity, visual appeal, preservation, quality of preparation and authenticity. Descriptions mention restorations if present.
In regard to the Invertebrata, Barrande, and a higher authority could not be named, asserts that he is every day taught that the palaeozoic animals, though belonging to the same orders, families, or genera with those living at the present day, were not at this early epoch limited in such distinct groups as they are now.
"On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life" - Charles Darwin
the debate of "do you declare a box that has vinyls and a few art prints under tariff code 8523.80 or do you need to declare the art separately even though there is no listed material value to the prints and there is also no duty fees for those"
This floating alien egg is Octameroceras, they're part of a group of cephalopods called Oncocerids which diverged earlier than the nautiloids and ammonites.
As they reach maturity, their shell opening, the aperture closes in on their face creating these Giger-esque shapes, and we can only speculate what bizarre mangled forms the creature peeping through that opening would have.
[image credit: Stridsberg, S. 1 985 05 09: Silurian oncocerid cephalopods from Gotland. Fossils and Strata, N o. 1 8, pp. 1-65. Oslo ISSN 0300- 9491. ISBN 82- 00- 07575-3.]
Even if the few fossil species which are common to the Old and New Worlds be kept wholly out of view, the general parallelism in the successive forms of life, in the stages of the widely separated palaeozoic and tertiary periods, would still be manifest, and the several formations could be easily correlated.
"On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life" - Charles Darwin