unicellular organisms. black drawing outline .

aeolosoma amoeba and animal aquatic biological biology black caudatum celled cytoplasm cytoplasmic difflugia doodle drawing extension fauna feet foot freshwater graphic hand illustration image invertebrate isolated line microbe microbiological microorganism microscopy nature nucleus organic origin outline paramecium protozoa pseudopodia pseudopods simplest single sketch spirostomum stentor unicellular vacuole white zoology