Sounds like a potato that got forgot about for some period of time.
I have been in a lot of commercial kitchens and I can tell you it is the reason I wont eat out hardly at all.When you walk into a Dennys restaurant and the sewer is backed up into the kitchen and smells like a sewer would you eat there.
This happened to me in San Antonio during an inspection.
I was wading in the backed up water in the kitchen while they were cooking.
I will go to court on it.
I have also been in 5 star restaurants in Austin that were filthy.
Greasy spoons that were as clean as a whistle.
Private rich folks clubs with dead rats in the kitchen.
Worth