Both are wild goose chases. The gate is an actual object in the Halo 2 mission Delta Halo. It is a floating box over the lake, that can be activated. People spent thousands of hours trying to figure out what it did, but nothing came about as a result. [url=http://www.bungie.net/en/Forum/Post?id=1120745]The Secret of Sandtrap[/url] was a hoax that fooled people into thinking that Sandtrap had something hidden in it, like the skulls, but far more discrete. Nobody found anything.