This is the ghost wall glitch - ZeroGravitas showcased it in his video already
.
In fact, I use it in some of my builds - for instance, I use it in my most recent build, the slot machine. Here's an example:
This is a state-checker mechanism that checks to see if the player got three symbols to match. Three skeletons are spawned from the statues on the left, and they move through the ghost wall to enter the hoik tracks.
The ghost wall can be achieved with hammered platforms or actuated hoik teeth that point in a direction opposite to the wall.