Traditionally, naval gunnery is challenging. Even with radar providing fire-control data, when fired, shells are committed to a flight path. This means an enemy ship can sometimes dodge the salvo with a radical change of course.
Guided missiles were developed in the 1960s and made their mark when Egyptian missile boats sank the Israeli destroyer Eliat in October of 1967 by using SS-N-2 Styx missiles. There was a problem with guided missiles, though — ships couldn't carry many missiles, even if they carried a big punch.
That said, a ship can carry many rounds per gun. For instance, the 16th Edition of the Naval Institute Guide to Combat Fleets of the World notes that an Arleigh Burke-class guided missile destroyer carries 600 rounds for its five-inch gun. That's a wellspring of ammo next to the standard load of eight RGM-84 Harpoon anti-ship missiles and up to 96 BGM-109 Tomahawk cruise missiles (and you know a Burke won't carry 96 Tomahawks).
The Italian company Leonardo, though, has come up with a solution. Their creation, called Vulcano, is a long-range, guided shell package. It comes in three varieties: Five-inch (awfully convenient for the Burke-class destroyers and Ticonderoga-class cruisers), 76mm, and 155mm (which could solve Zumwalt-class destroyers' need for a new round).
The Vulcano infra-red guided rounds have an effective range of just over 43 nautical miles, while the round's heat-seeking allows it to track ships, even if they radically change course. Granted, the heat-seeker is only fitted on the five-inch round, but the 155mm version has the option for a laser-seeker (much like the Copperhead round developed in the 1980s). In short, now a ship can pack a couple hundred small, anti-ship missiles.
Check out the video below from Leonardo Company to learn more about this new ammo: