What is a Gobbet?

Gobbets are, at the most basic, gobs of the broken Lux. The Lux is, of course, a giant ball of Light (Magic).
They bob about the night sky like drunken stars and are often more concentrated near the abode of a Magna.
Gobbet substance is often debated. Some believe the substance to be negligible, the balls being solely made of Light and not able to be touched. Others believe Gobbets have a slight slip to their surface, like a pat of melting butter, which accounts for the jaunty way they slice and bob through the night sky.
The purpose of Gobbets is also debated. However, that question has very clearly been answered by the only thing humans, or in fact anyone, have seen them do. They are used by the Magnas, hopefully in the best way possible.