The mine spider is a minor enemy in Jak 3. It is a small, fragile dark maker but very dangerous. They were encountered at the palace ruins in the mission "Reach catacombs via palace ruins", where they spawned from small pits in the ground.
Mine spiders are very small and very fragile creatures resembling harvestmen but with a very large, rather fluffy pods on their backs, colored pink and purple. They will self detonate on contact, acting as kamikaze obstacles.
It is generally best to ignore these, as they explode when touched with melee attacks and spawn infinitely until their spawn pit is destroyed. The first goal should be to destroy the pit. A large ground area weapon like the Wave Concussor is efficient against these enemies, though the spawn pit is easier damaged with a stronger weapon like the Plasmite RPG.