A 4" round terra cotta pot that grew root bound  with an unknown Vallisneria species, probably spiralis.  Use as-is or divide.  The rootball easily slides out of the pot for replanting or dividing into additional pots. This species grows FAST in my hard water under LED shop lights without any supplements, so it couldn't be much easier to grow. Nuisance snails are guaranteed to be included, Red neon blue-eye eggs are a likely possibility.