WARNING - This and Powerful currently appear to be broken. There are 24 cell fragments of each type, giving you 12 extra cells of life or energy if you collect them all. You start the game with 3 meaning collecting all 24 gets you to 15 of each. The other 5 are added each time you complete a main objective (end of wellspring water mill, end of bauer's reach, end of luma pools, end of mouldwood depths, and end of windtorn ruins if I am not mistaken). One of these five isnt currently being rewarded sometimes. I have done six playthroughs since the march 10th patch and have wound up on 19/20 on both life and energy 5 times even though I did 100% completion and 20/20 once. It may be best to wait to do your 100% run until after a patch fixes this.