Crinoidea

In spite of a vegetable appearance to which they owe the common noun of “Lily of sea” the crinoïdes (of the Greek krinon , lily, and eidos , form) belong to the animal kingdom. They are invertebrates of the echinodermatous group of the S, and as such they thus have a calcareous skeleton whose elements are organized according to a symmetry pentaradiale (founded on the figure five).

For the majority, the crinoïdes resemble a plant with flower fixed on sea-bed: they have a root and a long flexible stem finished by a chalice (or “Thèque”) provided with arm. Others crinoïdes are fixed on the bottom directly by their chalice, others still do not have fastener and carry out a pelagic life, in full water. It is by deploying their arms in range that these organizations filter sea water to find their food there.

The segments (or “articles”) which constitutes the stem and the arms of these animals, and that one names “entroques”, are circular or pentagonal and present a central vacuum.

During the primary Era and the secondary Era, the crinoïdes abounded and constituted true underwater meadows. While dying, they were dislocated and their extremely many fossil remains find today in limestones known as “limestones with Entroque S” or “limestones with encrines”. One thus finds of it consequently also in some Marbre S where the white circles of the articles of stem are located easily.

The crinoïdes form sumptuous bouquets. They are parents of the sea urchins and appeared starfishes there is more than five hundred million years. Because of their morphology, these alive fossils never could leave salt water. They are confined today in the tropical seas.

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