Spore pods are essential to the poison forest, as they will transform into a Thorn tree sapling if not within 35 blocks of one. They look similar to a giant red mushroom block, and spawn from thorn trees.
They often sit still, not turning until they roll forwards for 15 blocks, and sitting still again.
Spore pods will wander around randomly until encountering a player or getting 35 blocks away from a thorn tree. If they encounter a player, they will attack them by running at the player and exploding. A spore pod explosion does 5 hearts of damage, and damages no blocks.
If a spore pod does not detect a thorn tree within 35 blocks of itself, it will transform into a thorn tree sapling.