Hi,
The base rock would change on a daily basis, so hard to really give an idea on looks.
We do not order it in as base rock. We only order in top grade Fiji, Tonga & Timpora, but often some rocks come in not looking real good. So if we see any rocks that are really bad, far as being really dense, poor shapes etc, we will move those to a base rock pool.
So the majority of the pieces will either be really dense or just really big and not shaped great where they can't resell easily.
So the base rock would be useful to build the bottom part of your reef or used in sumps or projects where you just need bio support.