These look like molds
of shells. That is, if you poured plaster of paris into the shell,
let it set, then broke away the shell, this is what you would get.
Fossils form when the shell dies and falls to the bottom. As sediment
covers them, and in this case, fills them, over time it becomes
lithified (turns to stone). The age of what you have is hard to
dictate without other marker fossils that would indicate an exact
age. Hope this helps. ...Jack D.
These are fragments of ammonite shells with limestone filling.
Ammonites are extinct cephalopods, similar to the living Pearly
Nautilus. These are probably from the Cretaceous, or Late dinosaur
age. ...Allen A.
Not having a fossil
book infront of me this set are apparently pieces of ammonites ...SD
- These are pieces of
internal molds of various ammonites, probably Cretacoues as there
are extensive Cretaceous beds in Texas with similar ammonites....
Dr. David C.