According to Italy's ANSA news agency, a coroner is examining the skull to determine if it belonged to a man or a woman, and DNA tests will be conducted.
It is possible the remains are those of crewman Russel Rebello of India, whose body was never recovered. However, more likely they belong to a Sicilian passenger, Maria Grazia Trecarichi, whose remains were found on Deck 3. ANSA said her body was headless and missing a hand.
Trecarichi's remains were the last that were identified, in October 2013.
An ANSA video shows workers and police combing the wreck, which is at Genoa Prà-Voltri port for breaking. The authorities have been making a concerted effort to find Rebello's body, concentrating on the Deck 4 area where colleagues said he may have been when the ship capsized.
Thirty-two people died after Costa Concordia hit the rocks off Giglio in January 2012.