What is this marine fossil

[mr fossil]

Hello

i found these fossils on a island/mountain and they where only found at the peak(60 meters) I’m not sure what they are but they are definitely marine and quaternary but I’m I can’t tell what species this is or even what family.it looks very interesting 

mid anyone has any idea I would greatly appreciate it if you could comment 

thanks!!

[val horn]

I am guessing that it is all coral since one photo shows very clear coral.  there are experts on the forum who will not be guessing when they give you their opinion.

[connorp]

I'd vote for banded chert or something similar.

[JohnJ]

Test a piece of it with some vinegar.

[Al Dente]

Looks like a piece of speleothem.

[FranzBernhard]

Some kind of gypsum?

Can you scratch it with a fingernail? What happens when you hold a small fragment in a flame? Does it turn white immediately?

Franz Bernhard