Sarcodinas, Rhizopods
A: Foraminifers of Miliola race; the pseudopods, with the catched microorganisms only have the exit trough the opening.
B: Morphology of a foraminifer shell:
1.- Starting room or protoshell.
2.- Room
3.- Seam
4.- Opening
C: Diferent kind of foraminifer shells and the supposed evolution order.


The Protists include all the unicellular organisms, either of animal likeness (protozoa) or vegetal (protofits), being very difficult to distinguish between both kingdoms at this organization level. There are big disagreements among the specialists about the classification of those shapes, actuals or fossils. Some protozoa (foraminifers, radiolas, calpionelas) have great Geological importance, either as part of sediments or as stratigrafic fossils.

FORAMINIFERS (Paleozoic - Actual)
They are protozoa mainly from the sea, from the Rizopods group (represented actualy by the Amoeba). Their body is protected by a chitinous shell (organical substance similar to the one that constitute the arthropods shell) or calcareous. Their size is about a millimetre, but can reach several centimetres in the nummulites. They are excellent stratigrafical fossils.

RADIOLARIA (Paleozoic - Actual)
They are pelagic sea protozoa, from the Actinopoda group (which have radial cytoplasm expansions). Their siliceous shell is hard to disolve in the sea water after they die, which explains their acumulation even at great deepness ("radiolaria muds")

CALPIONELAS (Jurassic - Cretaceous)
They are pelagic sea protozoa, only fossils, from the Infusoria group (represented actualy by shapes that have vibratile ciliums). Excellents as stratigrafical fossils.

COCOLITOFORIDS (Paleozoic - Actual)
They are pelagic unicellular algas of very small size (0,01 mm.) which have calcarous plates called coccolits; their acumulation in calcareous mugs, during the Cretaceous, made the creta.

It is constituted by the joint of pluricellular alive beings, that generally can travel (though there are lot of fixed shapes) and haven't neither cellulose membrane nor chlorophyllous pigments.
The animals are represented from the begining of fossils time, that is, since 600 million years ago, and some of them, from the Precambrian.

The main animals group which are interesting Paleontologically talking are:
- Arqueociata (Precambrian, lower and medium Cambrian)
- Spongiae (Precambrian -Actual)
- Cnidaria (Precambrian - Actual)
- Annelide
- Bryozoan
- Braquiopods
- Mollusks
- Arthropods
- Echinoderms
- Vertebrates

They were the first organisms that could fix the sea water carbonate. The have an skeleton in the shape of cone, with a double holed wall that allows the water to pass trough: an external wall and an internal wall separed by an space (where the living stuff lived) occuped by partitions, some of them verticals radially placed and some of them horizontals.
Their reproduction is by Gemmation and sexual.
They use to live in big groups, forming , togheter with the blue algas, real reefs.
The Arqueociata are a phyllum different to the Spongiae and Cnidaria.

Soon we will talk about Spongiae.