This is ulva intestinalis (group of green algae) grown on plastic marine debris. Through this filtered image, we can see the microscopic tissue composition.
Colonization Mechanism of Living Organisms on Marine Debris
Conditioned film = molecules of sea water and colloidal dispersion
Bio-film = bacteria, diatoms, common types of unicellular phytoplankton
Macro fouling = accumulation of micro-organisms, algae and diatoms, and plants and larval settlements on surfaces
Composition of bio-film (2nd layer) is a key factor of conditioned preference for colonization of macro fouling (3rd layer).
(ref. 2005 Japanese Industrial Standards Committee).