A rather large (about 8 inches) very pale green squash!
There is another one on the way...
After some extensive research (aka: a Google search for "pale green squash") I think I've narrowed it down to what's referred to on websites as a "Lebanese-type" squash. But is it Magda or White Vegetable Marrow? Or is it a spaghetti squash that just hasn't turned yellow? (this would be something that may have been in our compost pile to start with... the other two, I've never eaten) I'm trying to get info so I can figure out how large to let them grow. Any ideas?
(Sorry the pictures are pretty terrible! This sucker is tough to photograph well. Color in the top picture is more accurate - very pale green)