xenoliths

n.(geology) a piece of rock of different origin from the igneous rock in which it is embedded

1. The basalt flow contained several xenoliths, mostly fragments of older sedimentary rocks.
   玄武岩流中含有几块捕虏岩，主要是较早沉积岩的碎片。
2. Scientists study xenoliths to understand the composition of the Earth's mantle.
   科学家研究捕虏岩以了解地幔的组成结构。