Magical Anomalies are creatures resembling a ball of rock about as big as a head, held together with glowing magicka with a long wispy blue tail reminiscent of a comet. They attack by ramming themselves into an enemy.
Anomalies appeared in Skyrim as a result of Ancano messing around with the Eye of Magnus. A host of them attacked Winterhold when Ancano activated the artifact and Ruptures which generate Anomalies still pop up around the various cities in Skyrim occasionally.