US 5944449 A abstract non abrasive and non shielding pads are attached to the at least one side of concrete elements with polymeric based fasteners that are embedded into a cast material such as concrete when the latter is soft a flexible rope is laced through the center of each element in two directions to form a mat in a row column array and a groove is established to interconnect two mats together adequate spacing is provided between each element to allow the mat to conform to an uneven seabed or structure the non abrasive non shielding pads separate the elements from the underwater installation to prevent the elements from scratching and permitting cathodic protection of the structures grooves are provided in selected elements and loops are provided at the outer edges of the mat to enable several mats to be linked together application_number US 4228298 A description the base component of the present invention is a concrete element although there are a number of suitable shapes the preferred embodiment is shown in fig1 the best shape for the concrete element 10 is two symmetrically opposed elements such as elements 11 however other shapes such as conical elements with a tapered surface to a face can be used any geometric shape can be used provided the shape can be tempered and have at.