No more guesses? Well, I thought it might be the front fuselage of a Vampire F3; the part between the cockpit and the nose-cone but with most of the top hatch covers shattered and missing. Then again, maybe it's not aviation related at all.
If it hasn't disappeared back into the shifting sands on Tentsmuir beach you can find it, when the tide is out, about half a mile North East of the end of the runway at Leuchars.
I have nothing else to hand so - open house...