At the head of the planarian there is a brain under the eyespots. From the brain, there are two nerve cords, which connect at the tail. There are many transverse nerves connected to the nerve cords, which make it look like a ladder. With a ladder-like nerve system it is able to respond in a coordinated manner.
Adventure mode. From Diablo Wiki. Adventure Mode or AM is the primary end game type of game mode introduced into Diablo 3 in the Reaper of Souls expansion pack. Campaign Mode or Story Mode is the other primary game mode, where players must progress through the acts in order, complete quests, talk to NPCs, watch cut scenes, etc.
Puzzle Ring is a legendary ring in Diablo III. It requires character level 29 to drop. Bearing the Puzzle Ring will effectively prevent player from getting common items for crafting. The rare items dropped always have 6 affixes, and counter persists through death and changing locations. Items dropped by player, including those bought from vendors, will not be picked up by the goblin. Also it does not pick up the items intended for Transmogrification. As of patch 2.3.0, one may transmute this ring in Kanai's Cube (destroying it in process!) to open a one-time portal to Treasure Realm.