Here is a close up of the "high" profile concrete rubble and its position to the shore line north of the 1000 ft. pier at Ft. Desoto, St. Petersburg July 29, 2000.  This area receives high energy waves and experiences "sandblasting" .  This is where very irregularly shaped and colored Perna viridis specimens were found in the intertidal zone (some fairly high up in the intertidal zone).