Answer:

ALGA

Answer	Crossword Clue
ALGA	Aquatic plant
ALGA	Birdbath organism
ALGA	Giant kelp, for one

ALGA	Simple plant
ALGA	Kelp is one
ALGA	Kelp, for example
ALGA	Pond floater
ALGA	Aquatic organism
ALGA	Pond growth
ALGA	Seaweed
ALGA	Water plant

ALGA	Half a lichen
ALGA	Pond life
ALGA	A real piece of scum
ALGA	Pond organism
ALGA	Primitive plant
ALGA	Sea growth
ALGA	Lichen component
ALGA	Fragment of pond scum

ALGA	Pool life form
ALGA	Kelp, for one
ALGA	Aquatic eukaryote
ALGA	Bit of plankton
ALGA	Kelp or plankton
ALGA	Plankton component
ALGA	Rootless plant
ALGA	Kelp, e.g.

ALGA	One-celled plant
ALGA	Chlorophyll-containing organism
ALGA	Component of a lichen
ALGA	Phycological unit
ALGA	Oyster thief or mermaid's wineglass, e.g.
ALGA	Photosynthesizing aquarium denizen
ALGA	Marine plant
ALGA	Seaweed, e.g.

ALGA	Stagnant water problem
ALGA	Bit of pond vegetation
ALGA	Pond plant
ALGA	Stagnant water growth
ALGA	Tiny pond plant