Oh, I might know what you're talking about! I'm determined to make mine just as biologically complex despite the discrepancy in size. Once I get the bottom feeders right, I can (deliberately) add predators. I'm very picky about the plants I choose as well. They must go through a rigorous application process. Moss, on the other hand, gets free entry!
I never heard of that broccoli (I think?). I looked it up and WOW it looks beautiful! I regrew a broccoli in the lawn once. Needless to say it didn't turn out all that great..