These are large polished ammonite fossils
still embedded in the rock in which they were found. The largest ammonite measures 9" wide. Many other fossils including clams and gastropods can also be seen in the rock. The ammonites are Cretaceous (Albian Stage) in age or approximately 110 million years old and are quarried in the Mahajanga Province of Madagascar. The entire piece is 20" tall, 13" wide, and the base has been cut flat so that it displays well on a hard surface. This is a heavy piece weighing approximately 60 lbs.
Ammonites were predatory mollusks that resembled squid with a shell. These cephalopods had eyes, tentacles, and spiral shells. They are more closely related to a living octopus, though the shells resemble that of a nautilus. Ammonites first appearing in the fossil record 240 million years ago, descending from straight shelled cephalopods. The last lineages disappeared 65 million years ago at the end of the Cretaceous.