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A Petoskey stone is a rock and a fossil, often pebble-shaped, that is composed of a fossilized rugose coral, Hexagonaria percarinata. [1] Such stones were formed as a result of glaciation, in which sheets of ice plucked stones from the bedrock, grinding off their rough edges and depositing them in the northwestern (and some in the northeastern) portion of Michigan's lower peninsula.
This list of fossil sites is a worldwide list of localities known well for the presence of fossils. Some entries in this list are notable for a single, unique find, while others are notable for the large number of fossils found there.
Scleractinia, also called stony corals or hard corals, are marine animals in the phylum Cnidaria that build themselves a hard skeleton.The individual animals are known as polyps and have a cylindrical body crowned by an oral disc in which a mouth is fringed with tentacles.
Favosites is an extinct genus of tabulate coral characterized by polygonal closely packed corallites (giving it the common name "honeycomb coral"). [1] The walls between corallites are pierced by pores known as mural pores which allowed transfer of nutrients between polyps.
Fossils of this genus form Petoskey stones, the state stone of Michigan. [1] They can be seen and found in most Midwestern U.S. states. Hexagonaria is a common constituent of the coral reefs exposed in Devonian Fossil Gorge below the Coralville Lake spillway [ 2 ] and in many exposures of the Coralville Formation in the vicinity of Coralville ...
The corallites are usually large relative to different types of coral. Rugose corals will sometimes have dissepiments, which are curved plates connected to septa and tabulae. The symmetry can be distinguished by the orientation of septa in a transverse section of the coral. Rugose corals always display bilateral symmetry whereas tabulate and ...
Halysites (meaning chain coral) is an extinct genus of tabulate coral. [1] Colonies range from less than one to tens of centimeters in diameter, and they fed upon plankton. [2] These tabulate corals lived from the Ordovician to the Devonian (from 449.5 to 412.3 Ma).
Around 300 species have been described. Among the most common tabulate corals in the fossil record are Aulopora, Favosites, Halysites, Heliolites, Pleurodictyum, Sarcinula and Syringopora. Tabulate corals with massive skeletons often contain endobiotic symbionts, such as cornulitids and Chaetosalpinx. [1] [2]