Ferrofluid
Now this is a bit weird, it’s a video of a black liquid called a ferrofluid that reacts to the presence of a magnetic field. I’d go into detail about how it all works but I didn’t really understand the wikipedia entry so to make it simple black fluid creates pretty shapes when near magnet.
If you’d like to try something like this yourself just Google for ferrofluid as it’s not too expensive and could be fun to play around with.
