Large chunk of chiseled obsidian, a so called "core" was found in the sea near Naples.
from the remains of what is likely a Neolithic, or New Stone Age shipwreck near the island of Capri.
weighs almost 17.6 pounds (8 kilograms)
recovered the artifact on Monday (Nov. 20) on the seafloor at a depth of between 100 and 130 feet (30 and 40 meters)
It's not yet known where this obsidian originated, but there are deposits of it on some volcanic islands of the Mediterranean, including the offshore islands of Palmarola, near Naples, and Lipari, near Sicily.

The real artifact would be the boat itself, no chance they'll find any remains of that. Neolithic seafarers used long (~10 meters) canoes, some even had masts with a sail. They're also guessing these were used as catamarans, with dual body.
Neolithic seafaring technology was exemplified by five canoes from the submerged "La Marmotta" site under Lake Bracciano near Rome, which have been dated to between 5690 and 5250 B.C.
https://www.livescience.com/archaeology/chiseled-obsidian-recovered-from-neolithic-shipwreck-near-capris-blue-grotto