This artist is impressively good at coloring and shading their work:
I have my phone set to grayscale, on its darkest setting, with it's built-in additional dimmer set to max, and an app called Darker set to max. my phone has at best 1.5 percent brightness away from "cave" dark and yet, a sort of, implied color, remains. What I mean to say is, that knot looks red even in grayscale, and with that, this piece is excellently well made.