Related Clues:

• Tiny pond organism
• Bit of aquarium growth
• Bit of phytoplankton
• Lichen component
• Tiny aquatic organism
• Oxygen releaser
• Unwanted plant in a pool
• Agar source
• Unwanted aquarium organism
• Some plankton
• Chlorophyll plant
• Fish food
• Bit of aquarium gunk
• Bit of rootless flora
• Film bit