What is this toy called?

[BikeRunSki]

Saw some children playing with an intriguing toy today. It was a ball a bit bigger than a tennis ball. It looked like it was made of kNex or something like that. When thrown, it it opened up to the size of a football. What was it?

I don't know what it's called, but I do have one so I know what you mean.

Could it be a hoberman sphere?

Something like this?

www.wilko.com/en-uk/wilko-play-expanding-ball/p/0334760

We have one. Can be called hoberman ball but many places do generic ones

I had one of those in the early/mid 90’s and never worked out how to use it properly

Brilliant!! Thank you. Will get one for stockings! I start collecting stocking presents from September.