Because of their organic indolence, sponges are often classed as vegetables.
"The People's Common Sense Medical Adviser in Plain English" by R. V. Pierce
About three centuries and a half before the Christian era, the question, Are sponges animal or vegetable?
"Harper's New Monthly Magazine, Volume 1, No. 3, August, 1850." by Various
The sponge had been in use many, many years before it was given a place in either the animal or vegetable kingdom.
"Nature's Miracles, Volume 1" by Elisha Gray