Deepwell Cooker?

My great-grandmother had an old wood cookstove in her house she stuck by up until her death in June. I always remember her having this pot sunk into the stove top away from the fire that she'd cook stuff in. I looked into this and I heard it's called a Deep Well Cooker, however I've only been able to find it on Electric and Gas stoves. I don't know of it was priginal to the stove or a modification made later on, but one of the lids could be removed from the top and a pot put in its place.