召喚區裡，兩位隊員利用傳訊版傳遞動物圖片，外面的隊友們通過排序食物鏈來換取鑰匙碎片，第15屆智慧鐵人決賽進階關卡「鏈精術匙」，要求小鐵人們解開被封印的鑰匙，開啟真理之門。
In the summon area, team members are informed to guess what kind animals is inside. Members in alchemy area can use the information to arrange the food chain.The Key Alchemist acquire teams to get the key and unlock the seal.
關主吳培瑋、林承育解釋，這一關要先解出鑰匙碎片和鑰匙碎片的順序，通過三個不同方向的立體圖形，想辦法拼湊出鑰匙碎片的樣子，利用排列動物的食物鏈，再推敲出鑰匙碎片的排列順序。
The taskmaster explained, this side-task need to get a key, you need to obtain the stereogram of key fractures, and the key fragments. You will watch a picture and there is 3D diagram of ONE key. You need to arrange the key fragment with the correct order. As for the key fractures, you need to arrange food chain so that you can speculate the key fractures.
鑰匙碎片採用立體圖形，小鐵人們利用有限的時間記憶，不停翻動樂高模型，百思不得其解。這道關卡考驗生物、空間和記憶，而吳培瑋、林承育認為，最困難的就是空間， 因為並不是每個人都有好的空間感，而缺乏空間感更不能記憶。
The key fragment using the 3D diagram, teams just can use limited time to memory.This task acquire biology, sense of space and memory. The taskmaster think that the the most difficult part is the sense of space. Because there are less people good at that, and if you don’t have the sense of space, you can’t even memory.
進階關卡更深度地考驗著隊員們的全方位能力，召喚動物煉成鑰匙，更期待他們能夠打開真理之門。（記者謝安然、呂冠樺／採訪報導）
Advanced task acquires teams more abilities. Summon animals to get the key and they will unlock the seal finally. (Reported by Anran Xie and Lyu Hua）
