These worms have been cultivated on instant potatoe mix rather than oatmeal.  A “micro worm” is a common name for a nematode or roundworm found in the Panagrellus genus.  They range in size from 1-3 mm in length and roughly 50-100 microns in diameter, which is slightly bigger than vinegar eels. (By comparison, newly hatched brine shrimp are 450 microns in size, so even the tiniest fry can slurp down nematodes like noodles.) Female roundworms reach maturity when they are 3-4 days old and can produce 300-1000 live young in their lifetime, depending on the species.