Spilagmite は最大2～3体の Spider を住まわせています。最大数がいくらかは Spilagmite 毎に異なるかもしれません。もし Spider に欠員がでれば新しい Spider が Spilagmite 内部に生成されます。生成頻度は約2分毎に1体です。
Like Spider Dens, Spilagmites are surrounded by webbing, which will alert the Cave Spiders and Spitters inside if a creature touches it. When the webbing is stepped on, two spiders will come out at a time (provided at least 2 are inside the Spilagmite at the time). If any Cave Spider or Spitter is attacked within range of the Spilagmite, or the Spilagmite itself is attacked, then all remaining spiders in the Spilagmite will emerge to engage the threat.
If the spiders that emerged are not killed and lose interest in their foe, they will stay outside their Spilagmite and roam the area.
If an earthquake occurs, all Spitters and Cave Spiders that are currently outside and that still have an active Spilagmite (as their home) will return to it.
A Spilagmite is destroyed by mining it with a Pickaxe, Opulent Pickaxe or Pick/Axe, after which it'll disappear and drop 1 Silk and 2 Rocks, with a chance of an additional Silk and Spider Gland. It will be able to spawn spiders up until the second strike of the pickaxe.
Attacking an active Spilagmite will spawn all remaining spiders still contained within.