I have not been able to find out much about this one but I like it. It is a durable plant with tropical foliage. Part sun to shade seems to work best. Not hardy in our area but not hard to bring some cuttings in to over winter. The large leaves work great in combos and this year I would like to try some as an annual groundcover.  This is a hand me down plant so any information has been sketchy. There was a variety on Ebay called "Green Queen" that sounded pretty close. A way cool tough plant.

Sounds like Oysterplant is a rather succulent herb with a dense cluster of sturdy 6-12 in (15.2-30.5 cm) long sword-shaped leaves arising from a trunk-like stem up to 8 in (20.3 cm) tall. The leaves are a dark teal-tinged forest green on top and vivid violet underneath. The small white three-petaled flowers are hidden in boat-shaped purple bracts nestled in the leaf axils. Flowers and seed are produced all year.

Moses-in-a-Basket, Boatlily, Oyster Plant
Tradescantia spathacea