I've seen geometric patterns and it's very similar to tie-dye fractals that kind of pulse and move among itself. A friend and I had very similar experience of the patterns (no elves wasn't DMT). You'd see them only when looking close up at something, not your entire visual field. They conform to the object you are staring at. A cardboard box wilth all its micro texture and creases "generated" the patterns and your brain would interpret it moving, pulsing, distorting, adding color.

(I am not saying this as some kind of allure of the drug's effects, just interesting to think about why and how the perception change happens).

I think maybe it has to do with your brain trialing new pattern recognition algorithms.

warning more musing below

I mean what is to say how any signal from our perception should look or feel internally? Visually the input in just raw EM radiation. And our brain makes this vivid picture out of basically a field of numbers. In this case you could argue that the extra pulsing or moving is not from a signal in reality, but we also can easily be tricked with visual illusions into seeing a static image move while completely sober. https://en.wikipedia.org/wiki/Illusory_motion.

There is no "right" perception of reality, or at least ours is subjective to begin with. I think drugs just allow new patterns or patterns recognition "algorithms" a trial run. Our biology ended up as it is to keep us alive; it is not "poison" or wrong to try to re-jigger it temporarily to see what else is possible - as long as you are in a good situation to do so. (Or not, who am I to judge).