This is partly true, Dalton. Though a lot of what a symbol looks like is controlled by what the artist does inside the artwork. On the left is the current boa symbol, while on the left is the one I'm working on in light of the flatness issue.

The rattlesnakes will be a slightly bigger problem, since they are really quite rough-skinned, so they don't have a glow down the back like a boa does.

Incidentally, if anyone is wondering how these things are made with a view to making their own snake symbols, check out the brushes top right in this shot. Affinity allows me to draw a perfectly straight snake (which looks really odd considering they never lie in a dead straight line), and then convert that image into a brush. So once the initial drawing is done I can draw the shape and apply the image to that shape.

These are the original dead straight boas used to create the snake brushes.

It works a bit like a cross between symbols along and a connecting symbol, with the central section of the snake repeated as many times as necessary to generate the length.

I think the second option is a bit too plastic looking, so I'll probably use the third version below.

Snakes, fungi, mould and guano...

If you don't mind departing just a little from the Tome to get this one thing the way you want it to be, you can add a Color Key sheet effect to the CONTOURS (SEA) sheet, move it above the Edge Fade Inner sheet effect, and then draw a solid polygon of magenta where you want the hole in the contour to be.

Make sure the Activate Sheet Effects box is checked and ok.

@Bidmaron - This is the spot where I started looking, and the search for all the possible textures and symbols took me 8 weeks. There's no guarantee that I got them all, either.

https://maps.arcanum.com/en/map/belgium-1777/?layers=37&bbox=527930.4200425778%2C6537602.115436598%2C537499.3805210282%2C6541285.424737089

I might be getting slightly off topic here, but I made some rocks that can double as cliff material.

But we do need the stuff to generate the right sort of mood, so maybe not?