No maps are mentioned where "X marks the spot."
No films are featured with "X-rated sex."
An "ex who lives in Texas"? I think not!
X flashes the allure of the unknown,
The algebraic problem to be solved.
Poor Y may get an axis of its own,
But not the fame, though equally involved.
X penetrates mere visual appearance,
Its rays reveal the bone beneath the skin,
To verify your skeletal coherence,
Or check your teeth for cavities within.
One final fact which made my mind perplex:
Its shape is all concave and no convex.