Minecraft wiki entry for Magma_Block, associated text: Magma blocks damage most living entities standing on top of them, even if underwater, dealing 1 of damage every tick, which can be reduced to once every half-second with damage immunity. Shulkers are among the mobs unharmed by magma blocks. Walking into the side of a magma block doesn't cause damage. Magma blocks do not destroy items. Damage from magma blocks does not reduce durability in netherite armor. Damage taken is considered fire damage and is reduced by armor, the Resistance effect, and Protection and Fire Protection enchantments. The player can avoid all damage by sneaking, being under the Fire Resistance effect, or by wearing Frost Walker boots.