Super Metroid NTSC RTA Etecoon floor clip explanation

NTSC Dachora bombwall moonfall speed storage/build up setup explanation: (https://www.youtube.com/watch?v=JyihFZNVZA0)
1. In the video, one can only unmorph between the middle block and the ceiling because the ceiling tile up there is a downpushing slope tile, not a solid block, and this (rightmost bomb block coloumn) is the only dachora bomb wall block coloumn that has a slope tile above it that allows Samus to unmorph and be pushed down through the middle block.

2. The top left bomb block is there for 2 reasons. For one, if it wasn't there, then (one couldnt align to it as ball and) one would need to x-pixelperfectly position the ball before unmorph-clipping into the middle block, because if one is too centered, then one will not be able to just walk/wiggle out of the bottom block towards the left once the setup is finished. And the block also prevents Samus from moving bit by bit after every turnaround towards the left outside of the middle block and eventually fall out (after like 8 turnarounds and one needs to do 176 moonfalls there).

3. TAS wouldn't need the top left block because of frame-precise Hoandizi-Shuffle turnarounds in crouch when turning to the left without moving leftwards (and standing up with a short tap without moving sideways), but since Hoandizi-Shuffle only works to 1 direction, and because the furthest right block coloumn needs to be used, not even TAS could do this on the right side to then clip into the Dachora pit. So the top left block removes this frame-precision that otherwise is required, which makes the process much more lenient and faster.

4. For exactly the first  25 of the moonfalls, one should only do them with turnaround spinjumps towards the right but not to the left because one can easily fall out that way and get stuck in crouch a bit under the top left block and cannot stand up anymore, and has to restart the process. But once enough fall speed is gathered (so that Samus instantly lands and won't move sideways anymore), one can do a faster method with turnaround moonfall spinjumps in both directions alternating.

5. The positions of the remaining bomb blocks are unique and no other combination would work (because of the above reasoning, and because the top left block couldn't be 1 tile lower because then one cannot bomb out that pattern of remaining bomb blocks out of the wall because bombs destroy bomb blocks sideways and vertically), so this is barely possible #deerforceintendedit .

6. The suggested way of doing the first 25 moonfalls exclusively towards the right is to press and keep holding Jump and angle L (or R) all the time; and press Shot if Samus faces left, press and hold Right to moonwalk, and release Shot (which will make Samus automatically start the turnaround spinjump), and keep holding Right until one sees Samus standing again and facing to the right (and not anymore in crouch facing right) before one turns around to the left to repeat the process. This is important because if one turns left in crouch, one will move Samus to the left under the top left block and is stuck under it and needs to reset the process. The first few spinjumps will take a bit longer than the rest. One also needs to always standup by pressing Forwards in crouch (for animation-less, instant standup), and never by pressing Up because this resets the fall speed.

7. The reason why the fall-speed isn't reset there is because in the frame when Samus in spinning pose touches the ground, the game checks if it shall put Samus into standing pose, and for this it checks if Samus' upper body is (at least partially) covered/inside of solid block pixels, and if yes, then it will not allow Samus to land in standing pose, but will also not reset the fallspeed (which can also be observed at failed door-stuck x-ray-climb setups where Samus gets stuck in crouch, not standing-pose, and then one cannot use X-Ray, because fall-speed isn't reset and to be able to use X-Ray, one needs exactly 0 fall speed, so it needs to decrease to 0).
8. For the remaining, quicker moonfalls, the suggested method is to hold angle L (or R ) and Shot all the time; and to moonwalk and tap Jump in alternating directions (as shown in the video, except it can be done faster). Once Samus finally clips through the bottom block, one can simply wiggle out of it and run across the room (without jumping, falling from the slopes with armpumps, getting knockback, crouching, or standing up with Up direction press, which would all cancel the stored fallspeed), into the elevator room for a final moonfall.

9. Sniq on his own messed around with this chain of moonfalls in Dachora's room and figured out that with many repeated frame-precise inputs a player or TAS could use it to clip through the Etecoon room floor with it, and when he told me (ED) about it, we discussed how it could be made humanly doable, and I mentioned the idea of keeping a bomb block to the left to be able to align to it, which then completed the faster and more lenient setup.

10. As Sniq figured out, if the last moonfall is done in the Dachora bomb wall and Samus clips, if one has Grapple, one can use it to push Samus up (without resetting fallspeed) to continue the setup even further and beyond, even until Samus starts clipping 2 tiles into the ground it can still be continued but at 3 tiles clipping into the ground one would be stuck. And for other applications (since this block cluster setup is quite specific, especially the slope in the ceiling), this setup could also be realized e.g. with Speedblocks and using a CF at the correct position to get Samus inside the blocks (instead of unmorph-clipping into it from above). Such a situation would be provided in the WS R-Tank room, higher up, where Speedbooster, Moonwalk, and a CF together would allow to clip down to the R-Tank (which though isn't applicable for 100% category, since one needs Speedbooster already from Norfair).