Small shelly fossils

With the lower Cambrien a low diversity of métazoaires evolves/moves having:

a shell,
a exosquelette (external skeleton) tubular or conical,
of the plates of protection,
a carapace,
of the sclérites (left external hardened or composed of Chitin of animals with soft bodies, or parts derived from the wall of the body, limited by joinings),
of the spicules (siliceous pivot or limestone constitutive of the skeleton of sponges).

These elements are called S.S.F.s (Small Shelly Fossils or small shelly fossils) and were very widespread in the world. The SSF appear approximately 10 million years before the first Trilobite S and bring the proof of the existence of the Biominéralisation. They were particularly abundant with the Tommotien and frequent with the Atdabanien.

They are represented by sponges, molluscs, year, lobopodes, and other forms which seem to belong to no recent phylum.

The study of the fossiliferous layers in Siberia, China, Europe, and Australia brought back an unexpected range of the well preserved phosphatic microfossiles. For the majority they are tiny shells or désarticulés components (sclérites) of protective armor consisted many parts. These microfossiles became familiar. Distinct forms were identified up to now,

forms with hexagonal symmetry;
forms of probably open cups of simple sponges of Asconoïde;
form of simple tubes comparable with the tubes of worm of sabellid, probably indicating the presence of the tentacles former like the Lophophore S;
form of multi rooms.

In terms of abundance, the simple cups and tubes are most numerous, by the forms multi rooms,

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