There is an arrow that says you can go down further in PD 6. In this level, there are breaks in the spikes both above and bellow perimetre.
Screenshot HereI've never gotten the

and

at the same time to be able to try and ascend upward past the spikes. Nor have I unlocked the Unstable Explosive to see if that can do anything in this situation.
But seeing as there is still an unknown item to be found in the game, I thought I'd ask.