This afternoon Snowball wandered in, and apparently noticed it for the first time. He went over and walked on it. And a plastic bubble popped.
Snowball leaped back like he'd been shot. He barked and growled at the bubble wrap, going into attack position, ready to lunge if it so much as breathed (it didn't).
After a few minutes of glaring intently at it, he was apparently sure he'd killed it, or scared it into submission. So he went over to walk on it again.
And a few more bubbles popped.
He leaped off it, howling in terror. Ran like hell for the far end of the house. He's now hiding under Marie's bed, shaking all over.