The findings may provide clues to the formation of the Saturn's known moons and give insight into how Earth and other planets in our solar system may have formed and migrated away from the Sun.
Images taken with Cassini's narrow angle camera on April 15, last year show disturbances at the very edge of Saturn's A ring - the outermost of the planet's large, bright rings.
One of these disturbances is an arc about 20 per cent brighter than its surroundings, 1,200 kilometres long and 10 kilometres wide.
The object is not expected to grow any larger, and may even be falling apart. But the process of its formation and outward movement aids in our understanding of how Saturn's icy moons, including the cloud-wrapped Titan and ocean-holding Enceladus, may have formed in more massive rings long ago.
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"We have not seen anything like this before," said Carl Murray of Queen Mary University of London, and the report's lead author.
The object, informally named Peggy, is too small to see in images so far. Scientists estimate it is probably no more than about a half mile in diameter.
Saturn's icy moons range in size depending on their proximity to the planet - the farther from the planet, the larger.
Many of Saturn's moons are comprised primarily of ice, as are the particles that form Saturn's rings. Based on these facts, researchers recently proposed that the icy moons formed from ring particles and then moved outward, away from the planet, merging with other moons on the way.
According to Spilker, Cassini's orbit will move closer to the outer edge of the A ring in 2016 and provide opportunity to study Peggy in more detail and perhaps even image it.
It is possible the process of moon formation in Saturn's rings has ended with Peggy, as Saturn's rings now are, in all likelihood, too depleted to make more moons.
"The theory holds that Saturn long ago had a much more massive ring system capable of giving birth to larger moons," Murray said.