I'm pretty certain the cats are not to blame for this:
It's a pretty thorough disembowelling of the futon. Notice the yellow throw that was moved over first. With added cardboard box shreddings for a scene of complete devastation.
Firstly Digger notices the cotton tassels that tantalisingly hold the filling in place
Then Mojo decides to have a lie down which requires a quick dig before circling a few times and going flump.
The digging opens a tiny rip, right next to a tassel which Digger is keeping an eye on.
They take turns to poke said hole.
They take turns burying a tennis ball in the hole to surprise themselves with.
As the daleks would say: EX-CA-VATE, EX-CA-VATE
We used to have another futon sofabed years back, which Mojo dealt with in her puppyhood. Some things never change, eh?