seaweed, duckweed
藻 centers on water plants: seaweed and duckweed, both floating or submerged vegetation in aquatic environments.
藻 combines 艹 (grass/plant) with 澡, which likely contributes the sound ソウ and relates to water, together suggesting water plants.
The top 艹 is a plant, and the bottom 澡 looks like water (氵) splashing around a tree (木) with mouths (口) like bubbles. Picture seaweed swaying in bubbly water.
For ソウ, imagine a soul (ソウ) of a seaweed floating peacefully in the ocean: soul -> ソウ, and the seaweed drifts with the current.
algae; waterweed; seaweed; duckweed
seaweed
seaweeds; algae; waterweeds
marimo (variety of algae, Cladophora aegagropila); round green algae; Cladophora ball; lake ball; moss ball
seaweed
scraps of seaweed
diatomaceous earth; diatomite; siliceous marl; kieselguhr
diatom
brown algae; phaeophyceae
waterweed (any aquatic plant of genus Elodea, esp. common waterweed, Elodea canadensis)
cryptophyte
haptophyte
Closterium (genus of algae)
Chinese mitten crab (Eriocheir sinensis)
Ochromonas vischeri (species of golden alga)
coccolithophorid
star duckweed (Lemna trisulca); ivy duckweed
washed-up seaweed; stranded seaweed
dwarf eelgrass (Nanozostera japonica); Japanese eelgrass
floating watermoss (Salvinia natans)