'Fe' is iron's symbol in the periodic table which in turn is the abbreviation for the latin word ferrum that means firmness.

Iron is Earth's 4th most abundant element while it is found in its core, it is also naturally found as sedimentary rocks. These are rocks that formed millions of years ago when Earth first started its oxygenation process oxidizing iron particles in the atmosphere and sea.

Iron is used to build durable things. The idea of making smart contracts out of iron implies that they are also durable. This reinforces the notion of compiler correctness.