Very smallest miniatures available in the hobby?

[Fishkeeper]

I just found out that Exo Terra makes an 8" cube, and I now very much want to fill one with the smallest orchids I can find. Not sure if that'll ever happen, but, out of curiosity, what are some of the smallest orchids available?
And by "available" I mean "you can find this from orchid specialists online", not "there's a guy who imports 5 of these every few years".

I have a Haraella odorata, Bulbophyllum catenulatum, and a Ceratostylis pleurothallis (mini Cambodia) that are in the size class I'm thinking about.

I saw a really odd plant at a greenhouse earlier this year, one that would definitely make the list, but I don't remember what it was called. I think it was a bulbophyllum, and it had tiny pseudobulbs, maybe a quarter inch across, that were round and kind of flat. It didn't have any leaves or visible roots, and it crept across a piece of bark so tightly it couldn't be trimmed or have cuttings made.