It appears that one eye is growing. Gall is what the bumps look like and are caused by a bacteria. If you have other tubers of this variety, plant them and toss this one. If you have only one, you can try to plant this one but the risk is that the new plant may have gall on it's tubers.

I do have other tubers of this variety, but now that I think of it, at least one of the others had a larger weird bump like this and may have had it when I divided. Hopefully I didn't spread it to my other plants.