Think the best representation of the ships is from Stolen Intelligence. There's a chapter called Fragment that describes Fenchurch interacting with an unknown material. It's never directly stated, but I always assumed it was a fragment of the Lunar Pyramid. It gave him hallucinations when touched, and it did come off a Thrall that crawled it's way from the Hellmouth. Given the description, I'd say it's safe to stay mostly flat. Though, the insides are usually covered in geometric patterns. I would think the outside would have patches of it as well. 3. When I woke, I found that my headache had not improved. I prepared my armor and exited my bivouac to find a single stationary Thrall crouched nearby. It stood as I approached, but made no motion to attack me. I fired one shot, killing it immediately. Upon stepping forward to examine its corpse, I saw a solid black fragment of an unknown material embedded in its chest cavity. The fragment resembled a flake or a shard of some larger object, not dissimilar to a high-gain photovoltaic panel.