This is a close-up of an unknown species of mysid shrimp of the order Mysidacea. Pictured too are skeleton shrimp, Caprellide sp. which blend in perfectly with the sandy bottom. The blurry lines in the water background are where fresh water is percolating up through the sand and mixing with the salt water. The size of the grains of sand give you an understanding of the proportions pictured here.