This is a bag of rat treats.
It was once a whole bag of rat treats that sealed. It is no longer whole, now will it seal. One of the things that one needs to remember about rats. They are smart and will work hard to get what they want. This particular bag was a little too close to the cage. Just within rat arm reach, if they stretched. And stretch they did. Thankfully they only ripped the plastic and did not eat it. There were little pieces of plastic all over the cage, almost as if strewn in celebration. I wonder just how much time they spent in the night working on this.