Biodegradable!
I opened up a Rubbermaid tub with some UFOs in it and was horrified to find a bunch of little plastic bag pieces laying all over the top of the fabrics. Haven't had any mouse problems but I was afraid one had somehow gotten into the tub even though it was sealed tight and chewed up everything. Then I tried to remove the top project which was in a dept store bag and the whole bag disintegrated in my hands. There was just enough left of the bag bottom to read the word "biodegradable". That particular UFO has been in the tub about 4 years so now I know how long those bags last and they certainly won't be clogging up the land fill a hundred years from now!
And yes, I know I shouldn't store fabric in plastic bags but I really didn't intend to leave that one unfinished for so long. I just forgot about it.