Picture not super clear, but yes I kinda agree with Mani, it looks like a worm in an advanced stage and if it is a worm, the animal has a belly full of them and if it's that far advanced, the worms should be in the stool as well.......
Hi and welcome to TCS. I actually cannot tell a thing from that pic. Do you have a better pic? What is the approx. size of what we are supposed to be looking at? If not a worm, it could be some part of a toy or other non-edible object that your cat ate.