Abelian Sandpile · Self-Organized Criticality

Grains: 0
Topplings: 0
Avalanche: 0
Max height: 0

Click to drop grains. Each cell topples when ≥4 grains, sending 1 grain to each neighbor. The group of recurrent configs forms an abelian group — toppling order is irrelevant (abelian property). The fractal identity element has self-similar structure.