I had two big brains do some "eenernet" searching and apparently Freedom Rink's ice became rotten or honeycomb ice. It all has something to do with the Hydrogen bonds.
Rotten ice is loose term for ice that is melting, disintegrating, or otherwise formed, having water, air or contaminants between ice grains, causing the ice to be honeycombed. It forms on open water, when snow pack and ice are mixed together and other conditions. It may be transparent, causing it to look like new black ice. Though it may appear strong, rotten ice is weak — even several feet thick may not hold a person's weight (although it may hold a dog sled's weight). On land, it is difficult or impossible to climb. It melts more quickly than solid ice. Candle Ice is a form of rotten ice.
I don't think it was rotten in Jan-Feb when we spent all that time on it, but became rotten as the temps stayed closer to 32 degrees in late Feb early Mar.
Regardless - it was cool to crunch up and see the small, pencil-like crystals. We'll have to add all this to next year's Freedom Circle's Home School curriculum.
Thanks Chemist Uncle Ben and MIT Jon.