After careful observations the character of the submarine structures (megaliths) can be characterized as follow:
1. They are megalithic elements protruding from the sea floor, with a very peculiar aspect and geometric shapes (these are cubic, pyramidal, parallelepiped and crest-like blocks).
Side Scan Sonar images display details of the recurrent shapes of the structures. Clearly shown in these images are the lineal character of the structures, and the square chamber-like sectors surrounded by thick walls and extended corridors. These structures are not associated with any fault or escarpment; so its nature is yet to be resolved.
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2. Some megaliths feature flat and differently smoothed faces showing traces of scallop, an erosional feature similar to those observed in limestone that has been subject to currents under a turbulent hydraulic regimen (not laminar). Other megaliths present slightly rough surfaces. In contrast, the blocks that fall freely from the steep walls feature an irregular contour, are of a dark color and do not resemble the megaliths. The following pictures show two megaliths, one resembling a cube and the other a pyramid, a few cubic meters in volume.
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3. The lithological composition of the rocks forming MEGA and the submarine structures cannot be accurately identified without conducting direct observations of the elements and taking sediment and rock samples is required. The few samples available up today are of rocks exotic to the nature of the megaliths, as they are rounded erosional elements. Two rock fragments recovered from inside one of the submarine features in MEGA are identified as a volcaniclastic sandstone and a carbonate breccia. Both are old rocks, probably not related to the composition of the megaliths, so they are of allochthonous origin. How these rocks reached the area of the megaliths is not yet understood.
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