I was thinking yesterday that nothing is unique. Look around yourself and try to find one thing that doesn’t have any variety. Toothpicks? Nope. Plastic, wood, flat tip, pointed tip, etc. Q-tip? Nope. Large, small, with a nob so it can’t penetrate far into your ear, etc. Cotton balls? What grade of courseness do you want?
I can’t think of a single thing that lacks variety. Was thinking I’d put the question to you Dopers. Figure you’ll come up with a variety (pun intended) of unique things.
Fingerprints.
Snowflakes.
They’re all unique.
[sub]You keep using that word. I do not think it means what you think it does…[/sub]
Snowflakes come in all kinds of varieties. As do fingerprints.
I mean unique as in lacking variety. Maybe unique isn’t a good word. It kinda fits by definition but I can’t come up with anything better at the moment.
This best example I can give is a toothpick. Imagine that that brown piece of wood was all there was. They didn’t come in different sizes or shapes or colors. Just wooden toothpicks.
Unique essentially means “one of a kind”. It sounds like you are looking for things that are “of one kind”, otherwise known as uniform or homogenous.
How about stop signs?
The only things I can think of are from mathematics and physics.
Simple: 1 and 0 (what was the term in set theory for these two ‘objects’? [identity and something else, doh])
Constants: pi, and speed of light c
More complex: The Mandlebrot set, which is the set made from the divergence/convergence rates of all Julia sets.
Time, the spacial dimensions are very different, and we have no reason to believe there are other time-like dimensions.
Distilled water, then.
Black bin bags.
matches
Dunno that baboon I saw running around throwing rock and masturbating at the same time was pretty damn unique.
I’m not up-to-date on my chemistry or quantum physics classes, but I would guess that the basic parts of an atom are fairly uniform.
A proton is a proton.
An hydrogen atom is an hydrogen atom.
Just a guess.
A proton is good unless you count an anti proton as ‘a different variety of proton’. Hydrogen atom doesn’t work since their are different issotopes of hydrogen nucleus, and different energy levels of the hydrogen electrons so different varieties of Hydrogen.
Simillarly distilled water has varieties according to temperature (solid, liquid, gas) and issotopes (heavy water).
rubber band? the one i have now is likely more or less the same as yours…
Penguins? 
There are a few languages out there that are spoken by only a couple of people… I’m sure there’s at least one or two with only one surviving speaker. That’s pretty unique, right?
There are too many quotes to do here, so I’ll handle things list style.
Very small rocks.
simple, look in the mirror. (I take it you don’t have an identical twin)
Tallulah Bankhead.
Go to your local art museum
you may not see anything unique, but you’re likely to see the masterful works from which many things are copied.
(unless, of course your local museum sucks)
Read up on the work of Paul Cezanne. His works aren’t too unique looking now, but that’s just because his innovations have been utilized by countless masters of the 20th century including Picasso and Matisse. The seemingly mundane painting of fruit on a table can be truly marvelous.
In computing, zero (in 8 bits) would be written 00000000. If the number system covers positive and negative numbers, the first bit is a “sign” bit with 0 mean postive and 1 meaning negative. Hence 100000000 is “negative zero”.
So in computing “nothing” (zero) is not unique.
(Hey, I’m rotfl here. Oh well.)