Mula is the nineteenth, ruled by Ketu, its symbol a clump of roots torn from the ground, its deity Nirṛti — goddess of dissolution. The name means 'root'. It lies toward the galactic centre, and the tradition treats it as the segment that goes to the source.
Mechanically Ketu severs and releases; Nirṛti unmakes structure. Together: following a thing to the bottom — not destruction for its own sake, but the fact that seeing a root requires turning over the soil. So people of this segment have no patience with the surface account: they want to know how it actually is, and that digging pulls up things that were standing perfectly well.
Where you'll recognise it: unsettled until you've reached the bottom, intolerant of pretence and fobbing off, a few complete restarts behind you, drawn to philosophy or depth psychology, and occasionally pulling yourself up by the roots as well. Running well, you're the best at finding root causes: still looking at the cause while others circle the symptom, able to sit with someone in the deepest layer. Stuck, you pull up too much — digging out what was still growing, 'I'm after the truth' as licence to dismantle, or never rebuilding after the dig. Jyeshtha before it holds the umbrella; Purva Ashadha after it is rising water: once the root is out, the force that grows back up.