Rastellum Carinatum Oyster Fossil Authentic Madagascar Specimen Rare

Madagascar's Marine Masterpiece: Authentic Rastellum Shell

This impressive Rastellum carinatum fossil measuring 86mm x 33mm comes from the celebrated fossil deposits of Mahajanga Province, Madagascar, a region world-renowned for exceptional Cretaceous marine fossils. Rastellum was a highly specialized oyster with an unmistakable shell form—flattened, fan-shaped, and adorned with prominent ridges that radiate from the umbo (the pointed apex). These oysters thrived in tropical Cretaceous oceans between 100 and 66 million years ago, anchoring themselves in soft sediments where they filtered plankton and organic particles. The genus became extinct during the end-Cretaceous mass extinction, unable to adapt to the rapid environmental changes that included ocean acidification, darkened skies blocking photosynthesis, and collapse of food webs. The fossilization occurred as the buried shell underwent permineralization, with groundwater depositing minerals like calcite and silica into the shell's microscopic spaces over geological time.

Rastellum fossils are paleontologically important as biostratigraphic markers for Cretaceous rock layers and as evidence of how mass extinctions reshape marine biodiversity.

Invest in this scientifically significant and visually striking fossil specimen now!