Endless Anomaly Fragment
The only Anomaly Fragments I’m familiar with are the ones that you fight during the new event. Could you perhaps give us some more or better information?
that_shaman has it listed as an endless tonic in his most recent data mining post on Reddit.
Probably one that turns you into either the humanoid or spark version of the Ley Line Anomaly (or perhaps both randomly?).
Haven’t heard anyone mention it in-game yet, could be an item for a future event or just a very rare drop. The events have only been live a little over a day and a half, it wouldn’t be that strange to have it not show up yet.