The Prophet's explanation: Skyshards (and Sky Prisms) are a rare type of meteoric glass. Sometimes called "Shards of Aetherius", skyshards are shards of Aetherial magicka that carries the essence of Nirn. They are sometimes linked to Lorkhan, the missing god of creation.
Lady Cinnabar of Taneth "Aetherial Fragments": Surely you have seen a shooting star. This occurs when a piece of Aetherius, spirit-plane and source of magic, becomes dislodged and falls to Nirn ... When three shards meet, they reform into a silvery prism by unknown process and confer the power unlocked by the merger to a nearby being.
My question is: why are we finding skyshards in delves and dungeons ? If someone moved them, then they would have used their magic, unless they never found three of them !
During the afternoon of Loredas, 6 Sun’s Dawn 2e578 a big piece of Aetherius fell to Nirn. It was the first major piece of Aetherius to fall on Nirn in more than five hundred years. It scattered around the world as millions of shards. It was rapidly documented by Lady Cinnabar of Taneth in her pamphlet Aetherial Fragments that "... when three shards meet, they re-form into a silvery prism by unknown process and confer the power unlocked by the merger to a nearby being." The Order of the Black Worm, commonly known as the Worm Cult, reappeared in Tamriel shortly thereafter and some of its members are avidly searching said shards.
In the last week of First Seed 2e579, an arcane explosion occurred in the Imperial City — a night of storms, and trembling terrain. They named it the "Soulburst". That day Emperor Varen Aquilarios disappeared without a trace. His wife, Clivia Tharn, ascended to the Ruby Throne as Empress Regent under the guidance of the Necromancer Mannimarco. Ushering a time of increased instability within the Empire of Cyrodiil which finally grew into “The Three Banners War”.