Robert sent in the link https://crev.info/2018/01/official-saturns-rings-young/ … from January 3rd. Cassini's experiment, the Cosmic Dust Analyser, has found the micrometeorite flux of Saturn's rings is 'inconsistent with an old age' and they are estimated at between 150 and 300 million years ago. In other words, they could be much younger. The link favours a much younger age.
Meanwhile, at www.space.com/39261-ringed-asteroid-chariklo-giant-planets-secrets.html … Chariklo is defined here as an asteroid but further reading describes it as a Centaur (which behave in some ways like comets). Chariklo has a ring system – like Saturn. Is this also a recent phenomenon. Moe Mandelkehr famously advocated Earth having a ring system at one time (the Lord of the Rings and all that) – but it was a temporary affair.