Religious Cave In Greece

[The3rdhero]

hey, i was wandering if anyone knows of a cave in greece.
the is a church right at the side of it.
the story goes a sheperd and his sheep went inside to get out of the storm and and he was visited by somebody (an angel i think) and they put runes or something inside the wall.
in the back, there is a pool of water in the back which is meant to heal you.
if this rings a bell, any info about it would be excellent!

thanks v much :)

Godbless

[The3rdhero]

to narrow it down i think it's on the island Kalimnos, the place that sells all the sponges :P