Related Clues:
- Minuscule lake organism
- Tiny tank plant
- Bit of pond slime
- Brown alga rich in iodine
- Dashi ingredient
- Kelp, for example
- Bit of aquarium scum
- Oceanic source of iodine
- Underwater forest flora
- Aquatic organism such as plankton
- Vegetation in underwater forests
- Brown sushi seaweed
- Bit of 19-Across flora
- Bit of birdbath gunk
- Simple marine plant