The intricately carved monster was meant to frighten the enemy.
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"There seems to be something in his mouth. There seems to be a person in its mouth and he's eating somebody," Johan Rönnby, professor of maritime archaeology at Södertörn University, told the BBC.
Sandekjer believes it looks like a monstrous dog.
"It may depict the very ‘Grip Dog' that the name of the ship - Gribshunden - reflects," he said in a statement.
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The archaeologists are hoping to bring more of the wreck to the surface.
"The ship comes from a time just when Columbus was sailing across the ocean and Vasco da Gama also went to India," Sandekjer said.
"The wreck may give clues to the building methods used for those journeys," he added.
The "monster" is now resting in a waterbath at the Blekinge Museum storehouse, waiting for the preservation procedure.
"Last time it looked at the world, Leonardo da Vinci and Christopher Columbus were still living," Rönnby said.