The aspect of all these cryptocoins that we have been mining that most amuses me is the "halvening" ratio of decreasing number of coins rewarded per block at predetermined block height intervals.  That is, for the first x number of blocks, the number of coins in each of those blocks is y, and then for the next x number of blocks, the number of coins in each of those blocks is y/2, and so on to y/4 and y/8, etc.

If we were to build an actual physical structure for which the length of each of its four outer walls followed the same formula -- where the width of the each new level built upwards in height were half the width of the level below it, what would this structure ultimately resemble?!