Hello Tyrone!
This is a tricky one you are offering, for sure. I have never seen a convincing natural sponge material by itself, it always need some tweaking regarding to the kind of object you apply it on. Most of the time, too, a bump effect or displacement is pretty useful for that kind of material.
For me, the one you show don't do the trick yet ; there's something that doesn't match with the sponge effect ; or maybe it's still too close to stone or something to be immediately identified as a sponge material. Starting with a synthetic sponge could be a first step before this tricky one, no??