It's a amazing how much a carpet can inspire a cat!
He becomes 100% alert and tries to catch whatever may be living inside the folds. Of course nothing is there but if there was, he would own it!
Is it the smells? The softness of the material? Perhaps the washing liquid we used? What can possibly bring a mature and usually placid cat to such cat-heaven?
Momentarily he gets into "trance", his body a loaded spring, his claws fully in "seize and keep it" mode! But there is nothing there... I tend to think that he gets excited by the feeling of the wool under his paws.
P.S. And yes, this is a baby on the edge of the picture, but that's another part of our common life and a story we'll tell another time. Just for those of you worried, I was there the whole time keeping an eye on both of them (baby and cat)!