Academics disagree as to its exact use, about which the primary sources are vague. It has traditionally been assumed to be a type of shared anal hygiene utensil used to wipe after defecating, and the sponge cleaned in vinegar or water (sometimes salt water).Other recent research suggests it was most likely a toilet brush.
I found this.
The ‘toilet brush’ argument remains very much a minority view.
I very much hope so.
Perhaps they were dual purpose.