House mouse

I have a heat pad, filled with seeds which I microwave to heat up and sometime use it if my back hurts through too much gardening or, as last week, when I had a toothache.
It wasn't put away after I recovered from the toothache, and I noticed there were little holes it in and the seeds were spilling out, so I just thought one of the dogs must have picked it up and played with it. I sewed up the holes and thought no more about it until today I found the real culprit!
It seems to be happily eating these old seeds, which must be at least ten years old and quite well cooked by now!