Related Clues:

• Bit of scum
• Part of a pond problem
• Healthful seaweed
• Aquatic organisms
• Primitive water organism
• Chlorophyll-containing microorganism
• Spirogyra, e.g.
• Lake organism
• Bit of ocean life
• Useful seaweed
• Primitive plant
• Underwater growth
• Simple aquatic organism
• Birdbath organism
• Seaweed that provides iodine