If you have trouble keeping a goldfish alive in a simple bowl, the odds of you successfully maintaining a jellyfish are slim to none. But why go to the trouble of setting up a saltwater tank, acclimatizing your new pets, and feeding them planktonic eggs when Hexbug now has a perfectly believable robotic jellyfish Aquabot to entertain you?
Using a compact battery-powered ducted impeller inside, the Aquabot Jellyfish will spin and use its 18 tentacles to propel itself through one of 15 pre-programmed swimming routines. It's completely autonomous, though, so it's a sit back and enjoy kind of thing, but after it's gone into sleep mode after a few minutes of performing, you can easily bring it back to life by tapping on the tank or running your fingers through the water.
And at just $15 you'll never need to feed it, clean the tank, or do any other maintenance besides swapping in a new battery every so often. [Hexbug]