One of the main groups of single-celled zooplanton, as opposed to phytoplankton, are the foraminifera, relatives of our freshwater Amoeba, but with calcareous skeletons that one day will contribute to rocky, geological strata in warmer tropical open ocean and inshore waters. Chalk is comprised of this sort of protozoan skeletal mineral. Limestone is a partly metamorphosed product that owes its origins to tiny creatures like these. This foram is Globigerina.
Lizard Island, Australia (1988)
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