petrified or fosselized earthworm.

[tinkerwell]

I found this fossilized earth worm last year.. love this it's fun one to share

 

[A2coins]

I doubt a worm would fossolize lol

 

[Kray Gelder]

Kind of a fuzzy photo, but it's not an earthworm. Probably a burrow, left behind in some mud or silt on the bottom of a lake or sea, later filled with sediment and turned to stone. It is a trace fossil. Evidence of past life. Cool.