Seaweed leshys resemble small, waterlogged humans made out of green seaweed, with skinny limbs, webbed hands and feet, and long brown, green, or red hair. They wear clam shells which can protect them, but not any others, as if they were armour. Seaweed leshys constantly grow small bulbs filled with air, which can be given to other creatures to let them breathe water.
Seaweed leshys must be grown in saline water, from seaweed treated daily with bone ash to encourage algal growth.
Seaweed leshys usually dwell near or in the sea, rarely staying away from the sea for a long time out of pride. They are usually patient, preferring to wait and see what tomorrow might bring instead of making rash decisions. The exception lies with freshwater plants: seaweed leshys look down on them and tend to laugh when hearing rumours of freshwater leshys.