The Australian Institute of Marine Science has posted an article and a great video of a Pacific triton (Charonia tritonis) eating a crown-of-thorns starfish (Acanthaster planci). Click here. The article discusses the predator/prey relationship between the two.
This starfish eats coral polyps, so spikes in its population cause the whitening of parts of the Great Barrier Reef when they occur. Pacific tritons help keep the starfish population in check.