ive been trying to look online for either hints or answers but i cant find much so if you have got the achievment please give me a hint or something

chat help me idk how to damage him

im just having trouble please help me.

I have been trying to defeat the boss in level 8, but no matter how many times I try I don't seem to get it. I have been shooting it until it spin sand then trying to shoot the blue things on its back but idk how to defeat it.

i dont get what it means