Anchor for mooring of buoyant marine structures. The anchor comprises an elongated shaft with a mooring line attachment that is rotatable around the full circumference (that is, a full 360 degrees of rotation) of the anchor shaft. The lower end of the shaft comprises nose section, while the upper end comprises a tail section. A plurality of fins are attached to the nose section and tail section, and extend radially outward from the anchor shaft. While the number of fins may vary, one presently preferred embodiment has three fins in each section of the anchor shaft. The anchor is preferably configured (via design of the nose and tail section fin areas, shapes, etc., and the location of the mooring line attachment along the anchor shaft) such that less soil resistance is created on the nose section than on the tail section under the influence of a mooring line load, so that the anchor will rotate slightly about the mooring line attachment point under the applied load while penetrating deeper into the soil underlying the seabed.