What are these things?
When I get close to it I take damage, but I can't hurt it.
What does it do and what is it?
Terraria – this purple claw thing (Demon Altar) and what can I do with it
terraria
Related Topic
- Terraria – this red glowing thing I’ve found in Terraria
- Terraria – Does breaking a demon altar work with artificial ore veins
- Terraria – this block and wall type
- Terraria – this big Gold and Blue thing in Terraria
- Terraria – What damage type are “extra” damage sources
- Terraria – I’ve killed the Wall of Flesh but can’t get to the loot
Best Answer
They are Demon Altars which are not monsters - hence you cannot get the tooltip by hovering over them.
You use them to craft some 'boss' summoning materials Slime Crown, Suspicious Looking Eye and Worm Food, as well as creating the stronger pre-hard mode weapon Night's Edge.
Demon Altars can only be destroyed with Pwnhammer or Hamdrax after Wall of Flesh is destroyed. Trying to destroy Demonic Altar before defeating Wall of Flesh, you will take half your current health in damage minus armor, no matter the tool. Pwnhammer is acquired by defeating Wall of Flesh.
Destroying a Demonic Altar will "bless" your world with decreasing amounts of ore, starting with Cobalt, then Mythril, then Adantium and then starting the loop again. This means that it will convert random blocks into whatever ore it is blessing your world with.
It will also place Ebonstone/Pearlstone in random locations underground, allowing Corruption/Hallow to spread faster and from multiple locations.
Source: Terraria Wiki