Abstract: An anchor for mounting to a hollow wall made of friable material comprises a proximal flanged end adapted to be engaged by a rotatable tool to rotate the anchor about a longitudinal axis thereof and to cause is to gradually engage the wall. The anchor also includes a distal end adapted to cut through the wall as the anchor is rotated, and a shank extending between the proximal and distal ends. The shank includes at least one expandable leg that is in a collapsed position thereof when the anchor is rotated to mount it to the wall and that is located distally beyond a non visible surface of the wall once the anchor has been mounted to the wall and is in a first position thereof. The wall anchor includes an outer thread that securely engages the wall. A threaded fastener, e.g.