Y'know...if the Gnomes of Spelljammer can market Giant Space Hamsters (including the Miniature Giant Space Hamsters), why can't the Kobolds of Spelljammer sell mini-mimics?
I sense an Alien-style adventure, in which an unscrupulous Kobold Merchant (What?) sells off a litter of immature standard Mimics as adult mini-Mimics. If you get Tom Wham to do a boardgame version, it could be called Awful Cute Things From Outer Space...