User blog comment:12th Supernova/750 chapters is a LOT/@comment-3425840-20140618154341/@comment-12.106.174.130-20140618181442

Agreed that sea stone seems a little too resilient. It seems surprising to have an item that just can not be broken. Since the key was destroyed to easily I would expect that it can be broken into, otherwise the factory assault is useless. Maybe Franky's beam level is the extent someone has to go to open.

Another thing that stick out is how did Law cut them in PH. When they escaped from the cage, only Law's were not seastone but it showed him cut Robin's with his sword. Is that how they would get in?