Lunar Fragments

Lunar Fragments are crafting materials dropped by the Celestial Towers during the Lunar Events. There are four types, each dropped by, and corresponding to, one of the Celestial Towers. They are primarily used at the Ancient Manipulator crafting station to craft several powerful late-game items, including armor, weapons, tools, wings, and others.

In addition to being dropped, a single fragment can be crafted by combining one each of the other three types. For example, if a player were missing a Solar Fragment but had a surplus of all the other types, they could combine a Vortex Fragment, Nebula Fragment, and Stardust Fragment into one Solar Fragment. This is done at the Ancient Manipulator.

Trivia

 * It is likely that the ability to craft a single type of fragment (Solar, for example) from the other three fragment types (Nebula, Vortex, and Stardust, in this case) was implemented due to the arduous process required to collect each fragment. Being a single Solar Fragment away from crafting the full set of armor would otherwise mean that the player had to fight the Lunatic Cultist, all four Celestial Towers, and the Moon Lord.