Fossil of Worms?

[Astro]

My 6 year old son found a strange large rock with a mid section of discoloration. The top of the rock seemed like limestone and the bottom something else. We split it open and he found this. The rocks were probably imported to support the local stream bed in Emmitsburg, MD. They look like worms, or roots in a rock. Any ideas?

[connorp]

Possibly some kind of trace fossil. Clearer pictures, including ones that show the relief of the objects in question, would be helpful. You say they're Cambrian aged in your tags. Why do you think that?

[Thecosmilia Trichitoma]

They could be trace fossils such as Thalassinoides burrows.

[Astro]

Thanks. I will look up what trace fossils are and also Thalassinoides.

 

I did not know what to put in tag, so I put what I could find on the internet of anything closely resembling. Native rocks in Emmitsburg I'm told are triassic red shale. This was clearly not native to the stream. 

[DPS Ammonite]

32 minutes ago, Thecosmilia Trichitoma said:

Thalassinoides burrows

Thalassinoides burrows are sometimes associated with shrimp like creatures  are not common in the Cambrian. More likely they are fillings of cracks formed in mud on the land surface.

[Wrangellian]

My thinking as well, DPS, whatever the rock's age.

[Rockwood]

4 hours ago, DPS Ammonite said:

More likely they are fillings of cracks formed in mud on the land surface.

Another possibility for this look that is slightly less well developed (less connected into a single pattern) would be syneresis cracks. They form when salt water sediments are inundated with fresh water.