Petrified coconut?

[lukashw]

Does anybody know what these are? Size and shape of coconuts embedded into rock on the coast, but hard like stone or petrified wood.

[DatFossilBoy]

I think they’re concretions of some some but not a fossil

[Rockwood]

I have a hunch that this is a clast. A stone that somehow got deposited in finer sediments. The worn look of it makes me think drop stone (from ice burgs) might be worth investigating. 

[pachy-pleuro-whatnot-odon]

Any volcanoes nearby, even if extinguished? I once used to own a couple of spherical stones that I had found in the German Eiffel (a volcanic region), which I had found as a kid and later found out to be volcanic bombs. Thus, I have no clue of the find circumstances for these things, but they are clastic and round, having been formed in the air after having been ejected by the volcano. As they are thus made up of igneous rock, and your "coconuts" look like they could be as well, I was reminded of them...

[Rockwood]

@lukashw Can you tell us the rock type ? Weathered limestone can look similar to volcanic rock. The bomb idea had occurred to me, but I read the rock as limestone.

[LabRatKing]

Need location data. Igneous fossils are ultra rare. Think Pompeii and Ashfall.

 

[lukashw]

The area here has a lot of seismic activity and is in a fault zone, but no volcanoes as far as I know. The nearby mountains are limestone and dolomite. I returned with an underwater camera and took some photos of the area under water where there are numerous column-like structures.

[Rockwood]

Can you estimate the diameter of the columns ?

[lukashw]

Approximately 5 or 6 inches in the above picture. Maybe 15-18 inches in the thickest part of the below picture.

[Rockwood]

Extinct fluid vents of some sort.

[lukashw]

Thanks! Do you think there is any connection between the underwater structures and the coconuts? This is all in the same area covering not more than a few hundred square feet. Nothing so out of the ordinary in the surrounding areas.

[Rockwood]

I can't tell from the photos which rock type it is. Volcanic eruptions, or erosion of limestone into an aquifer at some point would both seem to explain all the features equally well in both directions.