Tentabulges can regenerate and heal themselves after any amount of damage, and freshly regenerated bulges are very sensitive. This makes Blackrom sex all the more fun, knowing that there is no true risk involved, and once they regenerate, they can tease their partner even more, making them writhe. It isn't uncommon for the top to bite or otherwise sever the bottoms bulge completely, and then abuse the freshly regenerated bulge to the point of overstimulation.
You'll find that kismesis couples like to take advantage of this fact.