Possible mudcrack?

[Mjb99]

Found this on a rocky beach in Southern California and have no clue what it could be. Both sides are almost Ying yang like. Let me know if you have any clues!

 

[digit]

Could be cracked mud but more likely something along the lines of a septarian concretion.

 

https://en.wikipedia.org/wiki/Concretion#Septarian_concretions

 

We'll see what others with more experience have to say.

 

 

Cheers.

 

-Ken

[Fossildude19]

+1 for septarian nodule.

[grandpa]

@digit and @Fossildude19 are two of our most knowledgeable, most valuable (and personal favorite) TFF members/moderators.  So, I hate to disagree with them, but I will. 

 

I think you are certainly right in your conclusion; I think these are fossil mud cracks.  I have a few examples of the same type of fossils in my "fossilized weather" collection - which includes lightening strikes (fulgurites), water and wind wave formations, rain drops, etc.  I think of these as "weather" ichnofossils. 

 

[Of course to apply the term ichnofossils to weather, one would have to accept the Gaia hypothesis that Earth is a living being.  But - that theory does have such notable proponents as Lynn Margulis, biologist and former wife of Carl Sagan!  While I remain agnostic on the subject, awaiting further data to support the hypothesis, I'm comfortable with the term "weather Ichnofossils" to tag my "fossil" weather collection.]

 

Long and short, nice mud crack preservation.

[digit]

I like the term "weather ichnofossils"

 

Looking back at the photos above it seems that the cracks may only be present on two sides of this item and not evenly distributed around the rock. A septarian concretion generally has rather evenly distributed cracking all around it. The difference between the patterning on one side versus the other I took to be differential weathering but it could be the result of two different cracked mud layers one upon the other forming the two sides. I think @grandpa might be onto something here.

 

 

Cheers.

 

-Ken