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 variant 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 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 Fire Places or fire spawned by items, such as 
Red Candle or 
Bird's Eye, turn into Coal Spiders.
