From the rock, during a short period of time around May, "the rock cries !!!" and small amounts of water are dropped from small holes on the rock and collected by the inhabitants with spoons, which are used to treat eye diseases. That's the reason this place is called "Penedo da Fonte Santa", wich means "The holy rock fountain".
The scientific explanation relates to water retained within the rock and with the first heat days (May) undergoes evaporation and falls by gravity at the lowest point of the rock.