Who is this fellow?

Question

I just discovered a fellow running on the guava tree. I was wondering what this insect is and its functions?

I have attached the image and I currently live in India.

Answer 1

This looks like Umbonia crassicornis collectively known as thorn bugs defense mechanism to fool their predators as thorn. Not sure about it's functions in garden, but I remember playing with them by dropping them on their head and looking at them struggle to come back on their legs, when I was a kid.