Pholus is (just) an asteroid. Pholus was a centaur in the myths. In astrology Pholus is the symbol of turning points (of no return) – the catalyst – and of shooting your own foot… Pholus is there when a bottle is uncorked. That is the theory. And I think that the examples here are in line with that theory.
http://www.astromarkt.net/astrology_to_study-html/pholus-aspects-html/