Agraduate student finds an organism in a pond and thinks it is a freshwater sponge. a professor thinks it looks more like an aquatic fungus. how can they decide whether it is an animal or a fungus?

By the structure of their cell wall

Explanation:

Fungus cell contain cell wall with a chitin in it. That differs them from animal cell that doesn't have cell wall, but also differs them from plant cell wall which contains cellulose.

Fungus is a eukaryotic kingdom which contains microorganisms such as  yeasts and molds, but also macroscopic forms such as mushrooms.

Fungus are heterotrophic organisms, often decomposers with high  biodiversity.

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