Board Thread:General Discussion/@comment-30390828-20161120192150/@comment-28517148-20170823220252

There is no text in citation box so i don't know which post of mine you are refering to. its not clear if they last forever - events between Chara's death an Frisk fall into Underground do not take that much time :] I always assumed those canisters Asgore had kept them bound to the mortal world - game doesn't describe the purpose of those jars, so they also could serve as safe due to actual value of Souls.