Russian researchers have studied for the first time a rare fossil pearl found in Cretaceous deposits in the Voronezh region, estimated to be about 90 million years old, in a discovery that sheds light on the life of ancient mollusks.
According to the scientist, Lev Shelykhin, every discovery of this kind is of great scientific importance, because it contributes to deepening scientists’ understanding of how ancient mollusks lived and the mechanisms of their response to injuries and damage to which they were exposed.
He said: "The pearl was discovered in marine deposits dating back to the Upper Turonian period, near the village of Losevo in the Voronezh region. It is about 90 million years old, and it is the first fossil pearl of a bivalve mollusk to be scientifically described with this level of accuracy in Cretaceous deposits in Russia."
He explained that large bivalve marine mollusks were widespread in the seas of the Cretaceous period, and often had huge shells with a thick layer of the mineral calcite, which helped to keep the pearls inside them in good condition for millions of years.
He added: “Fossil pearls are much rarer than some might expect, because they contain a high percentage of organic matter, which reduces their chances of being preserved in the geological record. Therefore, each discovery of this kind not only represents a rare fossil specimen, but also allows for a deeper understanding of how ancient mollusks lived and their mechanisms of response to injuries and damage.”
The detailed study revealed that the pearl initially formed as a free-form pearl within the mollusk's body before later becoming attached to the inner surface of the shell, transforming into what is known as a "blister pearl." Researchers also found a small nucleus at its center, likely formed after a fragment of shell, a grain of sand, or another foreign object entered the gap between the mantle and the mollusk's body.
