Legend of zelda spirit tracks?

in the spirit tower floor 4 there is a section off to the right that you get to from floor 5 you have to have the boomerang to get there but its a switch or treasure (or something) blocked off by bombable blocks but you cant reach it because of a firewall (lol no pun promise ;P) i tried throwing a bomb, it blew up in my face(it hurt) and i tried getting zelda to carry the bomb but it blows up before she gets close! can she throw it maybe? and if that isnt it how do i get that secret?! its kind of ticking me off that i cant figure it out so if someone knows how? very much apreciated!