What do you do? a dissertation The thought was that pockets of molten iron trapped in the mantle layer could tunnel through the surrounding rock to create channels, or capillaries. This network of tunnels could have helped funnel molten iron towards the planet's center to join the spherical metallic heart that was slowly amassing there. 必須 2000文字以内 [bbs:youtube:(Youtubeの動画ID)]と書くとYoutubeの動画が貼れます。(例:[bbs:youtube:OQThUAQ0UN0])