82.Therefore，if the Earth began as a superheated sphere in space, all the rocksmaking up its crust may well have been igneous and thus the ancestors of allother rocks．

(特殊结构may well have been——可能是)

因此，如果地球开始时是太空中一个过热的球体，那么所有组成地壳的岩石都可能是火成的，因此成为所有其他岩石的祖先。

解析：

主句：all therocks may well have been igneous and thus the ancestors of all other rocks

从句1：if the Earth began as a superheatedsphere in space

从句2：making up its crust

主句中两个宾语部分igneous和the ancestors of all other rocks并列

从句1作为条件状语从句，修饰主句

从句2非谓语动词后置修饰主句中的主语rocks