"The fossilization of feces is strongly related to the elemental composition. The preservation of carnivore coprolites is favored by included skeletal fragments that are a source of calcium and phosphorous (e.g., apatite); more than 90% of coprolites have been observed to contain calcium phosphate as the primary mineral component" ---THE CONTROVERSIAL ORIGIN OF FERRUGINOUS "COPROLITES" by George E. Mustoe 

"The fossilization of feces is strongly related to the elemental composition. The preservation of carnivore coprolites is favored by included skeletal fragments that are a source of calcium and phosphorous (e.g., apatite); more than 90% of coprolites have been observed to contain calcium phosphate as the primary mineral component"  ---THE CONTROVERSIAL ORIGIN OF FERRUGINOUS "COPROLITES" by George E. Mustoe 

In the Early Pleistocene, about two million years ago, this pine cone cob was driftwood in the paleo Santa Fe River. The waterlogged wood sank to the bottom in a basin in the river channel. They became buried in a highly organic mud during seasonal flooding.

This anaerobic, low-energy burial preserved fine details such as bark and even insect borings. The cob is thoroughly mineralized with apatite -- it 'clanks' when two pieces are tapped together.  It is not "silicified" as labeled. 

This pine cone cob is dated biochronologically by the vertebrate fossils also found in the mud, notably Holmesina floridana, a giant armadillo. Fossils of the beavers Castor and Castoroides, muskrats, grebes, cormorants, ducks, and large fish suggest that this was a backwater pool in the river.

In the Early Pleistocene, about two million years ago, these twigs and bits of trunk were driftwood in the paleo Santa Fe River. The waterlogged twigs sank to the bottom in a basin in the river channel. They became buried in a highly organic mud during seasonal flooding.

This anaerobic, low-energy burial preserved fine details such as bark and even insect borings. The wood is thoroughly permineralized with fluorapatite -- it 'clanks' when two pieces are tapped together. The flourapatite comes from the mineral-laden spring-water of the river.

This wood is dated biochronologically by the vertebrate fossils also found in the mud, notably Holmesina floridana, a giant armadillo. Fossils of the beavers Castor and Castoroides, muskrats, grebes, cormorants, ducks, and large fish suggest that this was a backwater pool in the river.

.......... Family Dasycladaceae (extinct and recent)

. Family Receptaculitaceae (extinct)

...........Tribe Receptaculiteae [receptaculitids]

...........Tribe Cyclocriniteae [cyclocrinitids]

.............. Genus Cyclocrinites

Silurian-Ordovician

Wayne County near Richmond, Indiana

"Fossils of this order [dasyclads] are only rarely recognized by collectors.". . .

"Fossil dasyclads are globose to cylindrical or club shaped in outline. They grew on the sea floor to several centimenters in height.

"Internally, a central, noncalcareous structure, the stem or stipe, was surrounded by worled branches or protuberances (rays). . . . They are generally visible only in cracked or broken specimens.

"The primary branches or rays of some dasyclads are rounded at the tip; some have bristlelike or spinelike appendages; others have cuplike or prismlike tips that may be fused as an outer covering of small polygons.

"In cyclocrinitids, the end of each branch is expanded or branched to form a terminal rhomboidal plate. Each plate is one facet in a fused network of terminal plates of other lateral branches so that the surface of the whole body appears as a reticulate shell of calcareous prisms. . . .

"Cyclocrinites is generally a somewhat flattened sphere that has an indentation there the stem (pedicel) was attached. The main central axis was short; lateral branches were very slender, almost rodlike, and arranged in whorls around the central axis. The distal ends of the branches were swollen, and adjacent swollen branch tips coalesced to form the heads, which were polygonal (generally six-sided) in outline at the surface of the spherical body. These polygonal facets were calcified." . . .

Quote

Discussion and more images at:

http://www.thefossil...ae/page__st__80