Salinella salve, an organism described as a single layer of cells, ciliated on both inner and outer surfaces and surrounding a central hollow sac open at both ends, has been collected only once, by German biologist Johannes Frenzel, who claimed to have found it in the salt pans of Argentina in the late 19th century. Its body plan, which suggests a central digestive tract with a mouth and an anus, was unlike that of any known life-form. Composed of just one cell layer, Salinella seemed intermediate between single-celled organisms that perform all digestion inside the cell, and multicellular life-forms that excrete digestive juices into a central sac. Frenzel published his description of Salinella, along with detailed drawings of Salinella’s life cycle (shown), in 1892 in the journal Archiv für Naturgeschichte.
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(1) Back view of a mature Salinella salve individual.
(2) A mature Salinella salve individual seen from the ventral surface.