On your turn, do one of:
1. Place your coin on an empty cell (earns 1 random shell)
2. Use a shell from your inventory
Shell powers: Mine — Place on empty cell (invisible to opponent). If they step on it, ALL their coins vanish! Shovel — Remove one of opponent's coins. Flip — Convert one of opponent's coins to yours.
Opponent can see your shell count but not the types.