Spore counters are counters traditionally placed on Fungi, particularly Thallids. Many classic cards accumulate one spore counter each upkeep and can remove three of them to create a 1/1 Saproling token.
Sporesower Thallid accelerates spore production across your Fungi, while Sporoloth Ancient reduces how many counters are needed to make Saprolings. Proliferate can help an entire fungal colony ripen faster.