A concrete formulation, which undergoes controlled deterioration in water, that can be used for making anchors for releasably tethering submarine devices at the seabed. The anchor may have handles for a device release mechanism or a central hole for a central device release mechanism. The formulation includes additives, which cause the cement to transform into non-binding Thaumasite over a pre-set period of time, leaving only natural material on the seafloor.