Fossil or Petrified Wood?

[Renaebri]

Hello! I found this a while back around Melbourne, FL on the beach.

I've gotten two guesses on what it is, whale bone fossil and petrified wood. I originally thought petrified wood too but there's a spot on the inside where there's not so much of the gray... sediment? and I feel like it might be bone structure, the brown lines? I'll show what I mean at the end.

And thanks in advance! This was my first actual beach find and I know almost nothing so I'd love to hear anything you guys can tell from it!

 

 

(The brown lines around the top)

And an example I found online below, the one on the right has lines like it.

 

 

[Rockwood]

Looks like bone to me.