Second screenshot, in the slingshot room there's a removable brick with another slingshot that allows you to hit the previously unreachable sphere.
If anyone knows how to open the the second door in the first screenshot I would be delighted, I've been stuck on it for ages.
I've tried checking every room and wall in this floor, tried to check for secret passage in the two room above and found nothing, I'm getting quite close from a nervous breakdown here