Rock Spiders are small spider-legged stones and they were added to The Binding of Isaac: Repentance. They behave very closely to 
Spiders, but they are exclusive to 
Mines and 
Ashpit and skitter at a slower speed
Upon death, they turn into a normal Spider.
Variants[]
Tinted Rock Spider[]
Tinted Rock Spiders are essentially the exact same as Rock Spiders, however they have nearly twice as much health and, instead of transforming into a regular Spider, drop 1 
Soul Heart upon death. They are characterized by the "X" on their rock, which is similar to Tinted Rocks.
They do not spawn naturally; there is a chance that 1-2 will spawn upon destruction of a Tinted Rock while in the Mines or Ashpit.
Coal Spider[]
Coal Spiders behave very closely to Rock Spiders, but they skitter at a faster speed due to being on fire.
Upon death, it leaves a hot rock on the ground that despawns after several seconds. They can be shot to make them despawn faster.
Rock Spiders coming into contact with a 
Fire Place or fire spawned by items, such as 
Red Candle or 
Bird's Eye, turn into Coal Spiders.
