I nearly posted this last night:
So far nearly three pages of the Ceres scenario are describing alien biology that doesn't really affect the adventurers; they can observe it, take samples, etc., but most of what I've detailed so far doesn't really impact them directly. I think it's necessary for setting the scene, but it'll probably be about 30% of the scenario...
Except that a couple of hours ago I realised that with one small tweak to one of the things I was describing I had a much better plot. I'm pretty sure that the idea was in the back of my mind from the start, it just needed to work its way to the surface.
And I nearly cut a lot of the biology material, including the bit that's unexpectedly important, because I thought it wasn't going to be useful!
Oh, and another fun one for the space fans from xkcd: