I used Quick-crete cement, so it has little rocks in the mixture. When I was chipping away at the surface I really wanted to bring that look out. I imagine it will really have a nice look to it once the weather has had its way with it.
Yes, I'm actually curing another piece right now that has a sort of horned-skull look to it. It takes about 2 days for it to dry enough for me to work with it, I usually throw it in the oven on 180* heat to finish it off before it goes outside.