What is the name of these blocks (squares) and how do I access them in the code?

[atomic widget]

So, I'm trying to make a chunk/collision system for my 3D map (yes, the map is big), and I've been racking my brain since yesterday because of that, when I was going to turn off the computer, I noticed that there are these squares, as if it were a standard Godot tilemap, is there any way to access them within the code?

[jovial gust]

is it meant to have a texture?

@atomic widget