I was playing Terraria earlier, having just reached the Hell layer (~3000ft.) and after I killed one of those annoying imps, I got a message stating:

You feel an evil presence is watching you.

I read on the official Terraria Online forums that it means The Eye of Cthulhu is about to spawn at the surface. Unfortunately, after receiving the message, I saved the game and quit to look online for that message means (while still in Hell). When I reloaded the game and spawned at the surface, during night-time, Cthulhu wasn't there.

Save for breaking a Shadow Orb (which I do not have, nor can I survive in the Corruption with 7-8 Eaters of Souls spawning from all sides the instant I step into any corrupted patch of dirt), is there any other way to get Cthulhu back?