Like all insects, these caterpillars go through stages during which they shed their outer skin, including their heads
Other caterpillars would normally shed their skin and heads and leave them behind.
For weeks before they become moths, these insects carry their dead heads, stacking the old head to the current head.
The primary reason for the caterpillars’ head-stacking behaviour is, reportedly, to keep from being eaten.
Location: Dairy Farm Nature Park – January 2023
Thanks, Mr Jit-Leang Foo for the ID
I’m really curious how the stacking process happened, I hope can record this moment in future
Reference:
Meet ‘Mad Hatterpillar,’ the caterpillar that uses its old heads for defense