Italian archaeologists have unveiled the latest major find to emerge from the Roman forum - an ivory statue of an emperor, probably Marcus Aurelius or Septimius Severus .

The bust is unique - there are no other examples of statues like this made in ivory .

Very few ancient Roman ivory objects have survived to the present day because ivory is a biodegradable material .

Those that have not withered away over the last 2,000 years are mostly tomb decorations and small plaques .

The archaeologists found the statue at the Forum's Templum Pacis (Temple of Peace), which they started excavating last December .

The emperor is depicted in 'Greek philosopher' pose, wearing a tunic with his right hand raised and his head slightly inclined .

This has led experts to believe it may be Marcus Aurelius (emperor 161-180 AD), author of a famous philosophical work, Meditations .

The other likely candidate is Septimius Severus (193-211 AD), a prudent but ruthless ruler who came from the North African city of Leptis Magna (in present day Libya) .

The bust is 25cm tall and blackened by fire damage .

This may have occurred during the 192 AD blaze that devastated the Templum Pacis .

Emperor Vespasian (69-79 AD) built the temple in 72 AD to house the spoils from the suppression of the First Jewish Revolt by his son Titus - later emperor 79-81 AD - along with Greek masterpieces collected by Nero (54-68 AD) .

After the 192 AD fire, described by Roman historian Ammianus Marcellinus, the temple was restored by Septimius Severus .

The excavation of the site has also uncovered a beautiful, multi-coloured marble floor and parts of the temple's enormous columns .

The ivory-statue coup comes shortly after another jackpot find - a huge marble head of Emperor Constantine (305-337 AD) discovered in July at Trajan's Forum .

The 60cm-high head, which was found in good condition, showed Constantine in stylised glory, at the time of his triumphant entry into Rome after beating rival Emperor Maxentius at the Battle of the Milvian Bridge (312 AD) .

It was probably sculpted between 312 and 325 AD .