Bits of Bivalves, Millions of Years in the Making

I found this rock while hiking a few weeks ago and was curious enough about the markings to take some action.

I posted an image of it to /r/fossilid and asked the community what I was looking at.

Consensus was that yes, this was a fossil and the markings were most likely old shell bits:

Definitely looks like a shell bed to me. A bunch of bivalves have died and accumulated in this (mudstone?) bed. The significance of these is usually the way the shells have lined up, and the lack of other species in the rock despite the abundance of a certain type.

It may not be the fossil of an exotic dinosaur, but I'm still humbled to be holding the remains of life that's millions of years old.

It's also pretty remarkable that there's a community out there ready to identify the rock, plant or even 'thing' that you're curious about. Some the days, the Internet really does deliver on its promise of connecting people for the greater good.