Talk:Fort Collins/@comment-26365046-20161027174930/@comment-30347886-20161028155118

My theory is that the berries have been mutating over time, especially recently as they have started to become more active again.

There might be several strains of the berries, each one more advanced than the last. The first mutation made them indestructible, while the second made them capable of self-locomotion. The berries in the guy's pocket were of the original, non-mutated variety.