They attack by leaping upward to land on The Kid, dealing significant damage and telegraphed by an odd croaking noise.
The Kid encounters an enormous Lunkhead named Sir Lunky in the Burstone Quarry. This specimen is tougher, leaps much farther and deals more damage than typical Lunkheads.
Rucks remarks that prior to the Calamity, Sir Lunky was too stubborn to remove from the Quarry.
A Lunkhead's primary defence is a mask described as a stony eggshell. If The Kid lacks a weapon that can pierce armour, attacking the Lunkhead from behind is paramount - Lunkheads turn to face the player only a few moments before their next jump. Rolling underneath a midair Lunkhead is rather risky, but recommended if the player is surrounded on all other sides by falls and obstructions.