Fun but tricky question!

A sense of scale of this mammal tooth (I'm not certain it's a fossil) would be helpful. Is it the size of a person's "pinky" finger, or an ear of corn? And where was it found? I suspect on a beach.

If from a local beach, I suspect it's the canine of a modern marine mammal, probably Zalophus Californicus, the California sea lion, the commonest pinniped (flipper-footed carnivore) around here. A quick trip to the natural history museum could confirm this.

Sorry I can't be more definitive, but that's my best guess given the information provided.