On the cliffs near this village is Bosigran Castle, a small promontory of bold granite rocks, across which the insignificant remains of a thick stone wall are believed by some to indicate that here is a specimen of one of the so-called cliff castles.
A large block of granite in the centre, covered at the top with rock-basons, is called the Castle Rock; and near this a large stone, scooped, as it were, through the top, is known as the Giant’s Cradle.
At the distance of a few yards from these, nearer the sea, is an excellent logan stone, a slab of granite over nine yards in circumference, with rock-basons on the top. A slight pressure upwards, or standing upon it, causes this rock to vibrate throughout its whole length.
From Rambles in Western Cornwall by the Footsteps of the Giants by J O Halliwell-Phillipps (1861).
Oh, basins, saw those. Another sterling folklore response (pity? no, admiration, nay, awe).