Beautiful stone with dendrites & ? and other anomalies in concrete rock

[Lone Hunter]

The apartments I live in are doing plumbing excavation and this was dug up, couple things caught my eye so drug it home. It's a very pretty variety of rocks to be mixed in cement if that's the case, couple strange things one in first pics, (not the rock) then there is the stone with unusual dendrites I'm assuming, what is the thing they are growing around in center?  Whats with all the tubular shapes?  Sorry for picture quality my lens getting scuffed up.  Except for first three pics all the rest are same stone, I became slightly obsessed with it

[FranzBernhard]

That´s the way to go! Looking for fossils and rocks in broken up concrete!

 

I don´t know, what this anomaly could be. I don´t get fossil vibe, though.

 

Franz Bernhard

[trilobites_are_awesome]

Looks mineral to me.

[TqB]

Could be chert which often has dendrites on fractured surfaces.

[Baking Geologist]

Looks like a dendritic chert nodule

[MarcoSr]

Really nice dendritic specimen.  If you believe the theories of Marco Campos-Venuti in the below book, you have a nice example of dendrites caused by biological influenced processes in a mineral (a biomineral).

 

 

 

 

 

Marco Sr.