Hedgehog(Sicilian Kan)
Very similar to the hippo. A flexible system-like opening against 1.e4. It's called the hedgehog because on the third rank, blacks pawns are like spikes pointed at almost every square on the 4th rank. Basically, Black sits back and waits for white to overextend. Black tends to get closed positions in this opening. Although the only con to the hedgehog is that black gives white a space advantage and at the higher levels, white usually capitalizes on this factor, so I don't recommend playing the hedgehog above 1900.
Image credit: the chess world