A 400-series Roomba side brush, shown below,
is an acceptable toy, as far as cats are concerned.
How do I know this? Let me tell you a brief story.
Last weekend, we ran our Roomba in the kitchen area, as we generally do on weekends. When we returned, we found it out of battery power (unsurprising) and without its little side brush, which does have a tendency to occasionally fall off.
We looked in the Roomba's vacuum chamber, as it has been known to eat its own parts, but did not see the side brush.
We looked around the margins of the kitchen area, but did not see the side brush. We looked harder, in all the corners and crannies that the brush could conceivably have escaped to under its own power, but alas, to no avail.
We did hypothesize that perhaps one of the indoor cats had thought it was a nice toy and made off with it to some completely unrelated corner of the house. Superficial inspection of the usual spots (under the futon and the dining table) also failed to turn it up. I went ahead and ordered a replacement brush off of Amazon yesterday.
Guess what was sitting in the middle of the living room floor, innocent as you please, when I got back from church this afternoon??
Well, it'll be good to have a spare around, in case the cats kidnap the side brush for fun and games in the future. Meanwhile, I wonder if I should go look for my umbrella under the futon as well...