The narrow, tube-like body of intrusive igneous rock that cuts across existing rock formations is called a dike.

Here's why:

* Intrusive: Igneous rocks that form when magma cools and solidifies beneath the Earth's surface are called intrusive.

* Dike: A dike is a tabular (flat) body of igneous rock that cuts across the layering (strata) of pre-existing rock.

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