At the early attempts, the cable failed and when it was taken out for repairs it was found to be covered in living growths, a fact which defied contemporary scientific opinion that there was no life in the deeper parts of the sea.
【译文】在早期的尝试中，光缆铺设失败，不得不取出来维修。这时人们发现上面覆盖有生物，这推翻了当时科学界认为深海没有生命的理论。
【析句】句子主干为the cable failed and it was found to be covered in living growths，and连接两个并列句子，中间插入了when it was taken out for repairs为时间状语从句。it was found to be covered in…中，it指代the cable，found为find的过去分词相当于形容词，后面接不定式。之后a fact作同位语，which defied contemporary secientific opinion为定语从句修饰a fact，最后that there was no life…是opinion的同位语从句。
