A Chronovore was basically a giant, crystalline time bird. We once met a Chronovore named Kronos in Classic Who, who was summoned from an eponymous crystal by The Master. One thing led to another, and Kronos eventually destroyed Atlantis in one of the many different ends of Atlantis covered on Doctor Who. Go figure.

Podcast C064 The Time Monster > > > > > > > > > >

The Master summons a time pigeon and goes back to Atlantis where he finds a minotaur and other plot points.