Thanks Josephine for asking this in the telegram chat. In case someone else has wondered, here’s the “long answer”…
the short answer was going to be that it’s just a feature of the hashing algorithm.
the long answer is that the hashing algorithm is actually a board game called Othello. The rules of that game are really simple, and can be a maximum of 60 moves covering an 8x8 board using black and white discs, but the game tree is too large to map and so it’s never been completely solved. It also works really well as trapdoor hash function like the one used in ethereum and bitcoin. One positive difference is that the visual version of the hash (the board game being played) is often very interesting shapes. It is also sometimes symmetrical although it’s very difficult to tell which games will end up that way. So all the Clovers you see are actually board games, covered with black or white tiles. When the black player wins the Clover becomes black, when the white player wins the Clover becomes white, and when there is a tie the Clover is grey. Sometimes you’ll also have games where a tile is left empty because there is no valid move that allows a player to fill it. Or if one player completely destroys the other player before all the tiles on the board are fille. Those left over tiles are the color green like the board underneath.
Take a look at the album 
(link) for some good ones : )