Spider Pit-drop puzzle

[EvoluZion3]

I'm really annoyed with myself that I can't figure this out!

This is the first spider I see, trapped in a corridor. I can drop it via a pressure plate to the level below. If I get it on the centre square then it lands on a pad and lights up 3 of the 5 pressure plates behind me. The other plate just beams the spider back up again. I can't throw anything onto the lit pads either from above or below. What the hell am I missing?! Can someone give a cryptic clue?

[Hatman]

I'm really annoyed with myself that I can't figure this out!

This is the first spider I see, trapped in a corridor. I can drop it via a pressure plate to the level below. If I get it on the centre square then it lands on a pad and lights up 3 of the 5 pressure plates behind me. The other plate just beams the spider back up again. I can't throw anything onto the lit pads either from above or below. What the hell am I missing?! Can someone give a cryptic clue?

Here goes:

SpoilerShow

Ok if the spider lands on the button, the 5 holes open up (as indicated by the light).
You can put stones in the holes through the grates.
You wanna activate the 3 lit buttons at the same time.
Once you figured out where the light shines, put 1 stone in each of the (closed) holes. Then drop the spider on the button.
Also try activating all 5 buttons at once for a secret.
Lastly, in the lower middle room there's a wall switch that opens up another secret with a hint.

[EvoluZion3]

SpoilerShow

Thankyou Hatman - I had all that already I just forgot that you could 'place' something through the grates. I was trying to throw stones! I feel such a fool.

[Boxleitner]

Hatman!

I couldnt find that secret with the spider, where you hit all 5 tiles. If i hit the last one, it ports everything off the tiles.

Could you please reveal the answer?

(ive got the helmet. im just trying to see if theres a way to fight the spider or enter to top area where he walks)