What happens if I fall from 54.9 not to the black crystals secret gap, but through the spikes on the left? In 54.10 there is "ceiling" in that place.
Unfortunately, if you do that, you'll not get the black crystals. I've had that happen: same thing happens with umbrellas. The trigger for the crystals to appear is in the entrance that you normally pass through. Oh, and what I've discovered in TT.9 is that, once you get past the lemon, you just want to run for it unless the pineapple starts shaking RIGHT THEN... there's maybe a tiny amount of luck, but it's worth it in the end. I almost always make it just fine doing that. (of course, make sure to time it to avoid the blades!)