Male Beaked Whales have 2 tusks which stick out on the outside of their mouths. They use them to scratch each other, leaving patterns of scars. But they don’t seem to use them for eating, as they have a diet made up mainly of squid.
Recent research has used DNA analysis which suggests that they evolved as a secondary sexual signal to help females choose males within their own species. Apparently the various species of beaked whales are very similar in colour and shape. However the tusks do seem to vary significantly between species.
The above photo comes from the BBC, and you can read their article and see a video from their website.