Lava floor! That's awesome, I miss those days.
Also, about lava tiles: Outside our elementary school there were tiles of two different kinds, and they were placed pretty irregularly so sometimes it was very challenging to only walk on one kind (at least when we were kids, my legs are much longer now.) We'd call the smooth tiles butter, and the bumpy ones were crispbread. The fun thing was I was the only one in my class to choose to walk on the butter tiles. Everyone were always whining about how I walked on the wrong tiles, but I knew deep inside me that I was right and they were wrong.
(I don't know if crispbread is common outside of Sweden, so for those of you who don't know it, it's a hard, flat kind of bread, often uneven on the surface.)