"guano" is what you might be thinking of in that last sentence. --
dja
it was mentioned on several web sites, so I put it in.
guano is bat dung to my recollection, tho it may be high in Guanine ...
OK, sorry, I had changed it, but have now changed it back. It's also a mineral, wouldn't you know. <*shrug*> As long as the biochemical meaning is there, that's good enough for me.