Star dune: How old is the biggest sand dune on Earth?

Experts have worked out how old the biggest and most complicated type of sand dune on Earth is.

Star dunes can reach hundreds of metres in height and can be found in Africa, Asia and North America - and even on Mars!

The biggest- called Lala Lallia - is found in Morocco and researchers have dated it all the way back to the Upper Palaeolithic period.

That means it was formed around 13,000 years ago.

But what is a star dune and how are they formed?

Lala Lallia is 100m high and 700m wide. That's around the same height as Big Ben and the same width as around seven football pitches.

Star dunes get their name from their distinctive shapes which have multiple branching arms, and they're formed in places where winds change direction throughout the year.

Experts think Lala Lallia stopped growing for about 8,000 years after it first formed, before growing quickly over the last several thousand years.

Working out the age of sand dunes is helpful for scientists so they can understand the climate from thousands of years ago.

There is very little research done on star dunes.

Professor Duller from the University of Aberystwyth who published the research with Professor Charles Bristow at Birkbeck University thinks it's because they are so big experts didn't realise they were lo9oking at just one dune.