Related Clues:

• Chlorophyll-containing microorganism
• Spirogyra, e.g.
• Blob
• Biology 101 subject (Var.)
• Tiny organism (Var.)
• One-celled protozoan (Var.)
• Lake organism
• Slide subject
• Bit of ocean life
• Primitive plant
• Simple aquatic organism
• Organism on a slide
• Birdbath organism
• Unicellular critter
• Indivisible unit