Can't open .lyx file

[Drew]

Hi,

A friend of mine sent me a file with an .lyx extension
in the hopes of opening it up to see what it was.  It
was supposed to be some type of image file.

So, I installed LyX on my Linux box and proceeded to
open the file, but it won't open.

Is there any way that I can tell if this is indeed a file
for LyX?

If it's not, what else could it be?  What else would use a .lyx extension?

Thanks,

Drew