The correct answer is option 3, Morchella. This mushroom is commonly known as the `Edible sponge mushroom`.

Option 1, Polyporus, refers to a genus of mushrooms that have a polypore-like fruiting body. However, Polyporus is not commonly referred to as the Edible sponge mushroom.

Option 2, Agaricus, refers to a genus of mushrooms that includes the common button mushroom and the portobello mushroom. While Agaricus is edible, it is not commonly referred to as the Edible sponge mushroom.

Option 4, Sargassum, on the other hand, is not a mushroom at all. It is a type of brown seaweed commonly found in the Sargasso Sea. Therefore, it is not the correct answer for the question.

In conclusion, Morchella, or the Edible sponge mushroom, is the correct answer for this question. It is important to note that Morchella is a highly prized gourmet mushroom, known for its unique and sponge-like appearance.