Although all the specimens are awesome, the one that caught my eye, ros, was the chambered nautilus. Why? because it's the only time that I have understood geometry, and to my knowledge, the only time beauty has been demonstrated via mathmatics.
Fibonacci's golden spiral.
Oliver Wendell Holmes' beautiful poem, last stanza.
Build thee more stately mansions, O my soul,
As the swift seasons roll!
Leave thy low-vaulted past!
Let each new temple, nobler than the last,
Shut thee from heaven with a dome more vast,
Till thou at length art free,
Leaving thine outgrown shell by life's unresting sea!