I was referring to the rocks. I am certian I've been hit by a rock while standing next to it...
The hardest are the secrets in Scrabanian Temple, at the start, the one with the bomb, and the one in SE that has Sligs on both levels.
Actually, can't you do that Scrabanian Temple one at the start by standing on the far right of the screen and shooting? The slogs come out running to the left, so they'd have to turn around to get you...
As for the Stockyard Escape one, it's not that hard. It just requires you to place your jumps right.
I don't personally have any trouble with the bomb one(except always forgetting it exists), but I can easily see why others would.