Our globe is organized into three major layers: crust, mantle, and core. The mantle, which is hidden beneath kilometers of sediment and magmatic rocks, is typically inaccessible, and reaching it has been one of the primary goals of scientific drilling in the sea. In the 1980s, it was discovered that in certain parts of the Atlantic Ocean, the mantle surfaces at mid-ocean ridges, submerged mountain chains that generate oceanic crust and separate continents. Since then, multiple expeditions of the JOIDES Resolution drillship have focused on this stratum. Nevertheless, only five expeditions have been able to acquire more than 50 meters of mantle rocks, primarily along the ridges of the Atlantic and Pacific oceans. The IODP 402 expedition, funded by the International Ocean Discovery Program (IODP) with the participation of IODP-Italy, took place in the Tyrrhenian Sea under the scientific leadership of Nevio Zitellini from the Institute of Marine Sciences of the CNR (CNR-Ismar) and Alberto Malinverno from the Lamont-Doherty Earth Observatory (USA). The new study reveals that the geological nature of the mantle in "nascent oceans”, such as the Tyrrhenian Sea, differs from that of mature oceans and continental borders.  The research has been published in the journal Nature Communications, co-authored by the University of Pavia, CNR-Ismar, and the universities of Catania, Florence, Modena, and Reggio Emilia.