The Dark Volcano Sponge is also known as Svenzea zeai. This sponges' reproduction is no different than other sponges. The sponge releases sperm and eggs into the water. The eggs become fertilized and drift in the water until they land on a solid surface to begin to grow. The other way this sponge can reproduce is by a piece of the sponge falling off the sponge. This piece of the sponge gets carried by the water's current until it reaches a hard surface, where it can begin to grow as a new sponge.
This picture shows what a Dark Volcano Sponge looks like from above its "hills."