Any member here with knowledge in geology?

[Phoenikakias]

I have found this kind of stone digging a hole in my property. Could someone identify its kind (is it a fossil or what else) and could this find lead to some conclusions about the properties of my (sub)soil?

[Jerry@TreeZoo]

It looks similar to the coral stone we have in Florida.

[Phoenikakias]

... and it was found at about 138 m elevation. The whole mountain must have been once the sea bottom.

[Harry]

Definitely coral fossil

[Funkthulhu]

Bacherlors and Masters in geology here, emphasis in Sedimentology and ancient climate.

Do you have any other picture, perhaps at different angle and with a coin for scale?

FYI: Mt. Everest has seashell fossils near the peak, so coral can really end up anywhere if it's old enough.

[Phoenikakias]

Bacherlors and Masters in geology here, emphasis in Sedimentology and ancient climate.

Do you have any other picture, perhaps at different angle and with a coin for scale?

FYI: Mt. Everest has seashell fossils near the peak, so coral can really end up anywhere if it's old enough.

Sorry for the delayed answer, I had to find first some time for more pics. I do not think that size is of the specific rock is relevant because it probably is only a fragment due to previous palm planting. But here are some pics of bigger parts exposed by the dozer at an old time (and 20 EURO-cents coin for scale)

[Phoenikakias]

... and smaller fragments

[Funkthulhu]

Definitely marine conglomerates, as you can see from the shells. They may even be coral/oyster bed that has completely fossilized in place and then broken up later.

The third large picture is very interesting. It appears to have some sort of layered siltstone/sandstone inclusion. Considering the smaller pebbles visible in the other samples, and assuming they're all from the same formation. . . I would be pretty confident saying this was a near-shore/shoal environment that had a lot of interesting things mixed in before it cemented up.

If there weren't obviously marine fossil inclusions (shells) I would say this is a really good candidate for a glacial outwash or glacial moraine sample. They're known for having a mixture of every possible grain size from clay/silt up to house-sized boulders. Though, if those were fresh water clams. . . That might actually be a pretty solid explanation.