Two smoothed slabs of crinoidal limestones attached make for an attractive bookend along with another raw slab containing internal moulds of Crinoid stem fragments from the columnals forming stem. These layers of stem fragments have a distinctive 'screw-like' thread pattern and have been called screwstones.
The Form
An array of branching arms (brachia) is arranged around the top of a globe-shaped, cup like structure (calyx) containing the main body of the creature. In many fossil forms, the calyx was attached to a flexible stem that was anchored to the Sea bed.
The skeleton is made of the mineral calcite and consists of hundreds of individual plates of many shapes and sizes.
Positioning:
A great conversation piece and zoom aesthetics for the study or private library. (Note: composition and colouration will vary)
Crinoid Fossil Bookends (Pair)
Height: approx 17.5cm
Width: approx 11cm
Depth: approx 6cm
Weight: approx between 1469g and 1496g each
So what in the World are Crinoids?
Crinoids are marine animals belonging to the Phylum Echinodermata and the class of Crinoidea. They are an ancient fossil group that first appeared in the Sea's in the mid Cambrian era of at least 300 million years before the Dinosaurs. They flourished in the Palaeozoic and Mesozioc eras, however some survive to this present day. Although sometimes different from their fossil ancestors, living forms provide clues about how fossil Crinoids must have lived.
Chronological to GeologistsOccasionally, Crinoids can be a useful guide to the age of the rocks in which they occur.
Fossil Crinoids indicate that the rocks containing their remains were formed in a marine environment and were abundant in Palaeozoic rocks. They suggest the former existence of shallower water conditions. In the early Carboniferous, their rich remains (particularly stem fragments) were solidified into the rock called crinoidal limestone. Rare occurrences of complete fossilised Crinoids indicate rapid burial in quite possibly poorly oxygenated waters.Myth and Legends
Crinoids are sometimes referred to as 'Sea-Lillies' because of their resemblance to a plant or flower. In parts of England, the columnals forming the stem are called fairy money. Star-shaped examples of these were associated with the Sun by ancient peoples and given religious significance. Robert Plot (1640-1696) named these 'stellate' forms of star stones.