They are snakes

Limbless slithery reptiles with forked tongues, milky eyes, dry skin and ice-lolly-like tropical colourings.

Snakes.

This critter is mostly blank space, so I was forced to use some texture. I think it ended up ok. Only two levels to it, so it doesn't seem out of place next to the flat shading.

Top left was the original. The rest are hue-shifts (obviously). Top right is my favourite, with just the right amount of contrast. Also I never would have picked that colour for the tongue, but it works nicely. Seablue's tongue is also pleasing.

The hue shifts are just me playing around, seeing what looks best. Only the top right snake is the "real" thing. I'm still avoiding palette swaps.

As far as the linework goes, I don't think the snake's body lines up properly. I feel that this should bother me more than it does. I saw a quote recently - "Build it wrong, but build it." I'm doing that.

Trivialities: the forked tongue is squared off. I had to to get the right shape without too many nodes. I'm thinking of changing the corner style to rounded to avoid this. I'll lose sharp points, but I'll be able to use much shallower angles without getting ugly square ends. I suppose I could change the corner style case-by-case, but once I start doing that I'll be varying line widths and who knows where I'd end up.

Arbitrary restrictions. Woo.