Matthew had gotten some mice as pets. They were brownish-grey in color. I was helping him with them. There were several wire cages that had things that were tube-shaped and no bigger in diameter than the mice themselves. The mice could enter the cages through this tube and they could get back out either through the same or similar tubes. I was doing something to the tubes, though I don't know what or why. I was sitting on the floor and frequently picking a mouse up from one area of the carpet and placing it near a cage. I said something to Matthew about how odd it was that I was willing to sit there with these mice and that I was even willing to handle them. As I was sitting there watching them, I noticed that there were 6 or 7. I thought there were more than that originally, that one or more of the mice were now missing. He had bought them at 2 or 3 different times, and each time purchased the same number. We were discussing how many he bought each time so we could try to figure out how many were actually missing. I didn't know how long they had been missing and was imagining their little bodies lying dead somewhere.