seatang

Example:Land plants are photosynthetic organisms that do not require seawater to survive.

Definition:A plant that grows on land, as opposed to aquatic organisms like seetang.

Example:Freshwater algae are different from seetang in terms of the environment they naturally inhabit.

Definition:Seaweed naturally does not have a direct antonym, but if we consider the term 'freshwater algae' to mean algae that grow in freshwater as a comparison, it implies the opposite environmental context.