Guaranteed to Impress the Science or Math Geek

Wow.  I stumbled upon this awesome list of cheap gifts "guaranteed to impress the science geek" and while I'm not necessarily into all of these items, there were a few that I'd really love to see in person!  Here are three of my favorites (links included in image captions.)

To begin, who doesn't love a terrarium?  Here's one with a little twist - inside each EcoSphere are active micro-organisms, small shrimp, algae, and bacteria all acting as a self-sustaining ecosystem.

EcoSphere

Or how about Gallium Metal.  This silvery metal with a melting point of 85 degrees - so it literally melts in your hand!  Let it melt in your hand, then pour it into a dish or tray and it freezes back into a solid. Crazy!

Gallium

If something more practical suits you, check out this Klein Bottle - perfect for any mathematician.  A real Klein bottle is an open object with no inside and no outside (which can only exist in four dimensions) but this glass bottle in the third dimension can hold liquid... Interested?  Read about the math here.

Klein Bottle