[Doc Dubois] had been focusing all of his attention in the other direction, on Peach Pit and its iron-rich “children,†PP1, PP2, and PP3, nailing down their exact orbital parameters, taking high-res photographs.
PP3 was especially interesting. It was a congealed glob of mostly iron, similar in composition to Amalthea. It was some fifty kilometers in diameter. And it had a deep cleft on one side, comparable in size to the Grand Canyon, apparently formed by a collision that had rent its outer skin while it was partly congealed. Doob had begun calling PP3
Neal Stephenson