It is roughly composed of triangles, and pentagons.
A representation the layout of Dron.

Introduction

The great icosidodecahedron called The Dron is what the thousands of species that live here call home...

... But where are my manners? I'm Buhr, Buhr the Boneless. Nice to meet you. I will be your guide today. Yes I'm an octopus, Enteroctopus magnificus sapiens, and as you've noticed a well learned one, a Geomancer and Cartographer amongst many other things.

Now, let's get back to why you're here.

A Great Icosi-what?

Don't know what a great icosidodecahedron is? You're not alone. The vast majority of Dron (apart from the geomancer guild) don't know a donut from a mug.

Let's break down the introduction to what any salt worthy adventurer needs to know to last through the hour of night, when the Doom is at its highest, the hour when fire is snuffed out by the evil and cold dark that radiates from the shadows.

Before first. Nights in the Hull are evil, not your mediocre evil. People caught without shelter during the hour are mostly murdered, driven mad, or turned to something in between those two things. Do not go out at night if you can possibly avoid it.

First. Need Fire? Go ask the neighbor for some. Fire in Dron cannot be started unless by magical means or by bringing it from the fire mines underground. Spells are not freely granted to commoners, and if you want fire you should keep one yourself, or pay for it like we all do.

Second first. The Works? The underground cliff hanging pirate utopias? Those are a myth mothers tell their children to eat their surface dwelling cabbage soup. The small quaint villages in the shafts under our feet are not at all full of murdering renegades, bloodthirsty living roots or crazed mind flayer exiles. They are just different thats all.

Second second first. Don't trust anyone from a triff. Half-troll green men with random extra heads, tiny cannibals obsessed with blood and four arms? Those do exist, some hullians are just not like the rest of us, the outstanding citizens of this enlightened age.

Last first. When you run into a walking hill swarming with beastfolk on its branches, run the other way and pray the hill does not decide to follow you.

... And thats just the first thing about the Dron. But there's more, much much more.