Don't think I have ever seen that - you said it's the cone itself and not the dust cover (scratches head).

Does it look like the cone is just angled off center (like someone is pushing sidewards on the voice coil at the back) or something worse ?

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8