If you're looking for a science experiment to do with the kids and keep them entertained during the winter break, you can't go wrong with this.
The process is pretty simple. Start with Silly Putty, then blend in some parasitic copepods. These nearly microscopic critters typically live in or on fish, and have a strong urge to seek out new hosts.
Once you've achieved a sufficient concentration, the putty will start to behave like a living creature and be naturally attracted to cans of sardines or tuna. You can see a big blob of the stuff above reaching out for some dollar store anchovies.
Just kidding. This is magnetic Thinking Putty, a silicone putty (like Silly Putty) with magnetic particles suspended in it. Very cool stuff.