Hello! one of my coworkers brought in this fossil since they knew I was interested in that sorta thing and when I first saw it my mind went to coral but they said it was from California and was told it was a Mammoth molar, so I had to change my theory. While I know it is not a Mammoth molar it definitely has a tooth like structure, and in my opinion, could look like a heavily worn down Mastodon molar but I wanted someone who is an expert in this field/ knows more information than me to help with the identification.
I didn't get to measure it exactly but my rough estimate was around 13cm