I'm in middle school so just take what i say n make it sound really smart.
First they should see the main structure and then go into the details. If this mysterious organism is a plant it would have diiferent cells. Plant cells are called eukaryotic cells. The cell walls of these cells contain things like cellulose, and plastids (chloroplasts and chromoplasts). Then there's the endoplasmic reticulum and nucleas-the brain of the cell- and the central vacoules.
To see if it is an animal they should again look at the main structure and then go into the details. An animal cell is different it doesnt have a cell wall so right off the bat you can tell. Animal cells are fairly simple there's just the cell membrane, cytoplasm, and nucleas.
Both cells are very similar beacause they both have nucleas' cytoplasm', and cell membrane'. But plant cells have plastids to help other processes in the plant-like transferring sunlight into energy- while animals have the basic things. Animal cells don't have cell walls because no cell walls give flexibility which helps the animal move. So, as you can see, you can differentiate plants from animals by looking at their cells.
Hope you like my answer! Oh and you better mark it as Brainliest, no one else is willing to waster their time writing an open response for you. You should listen in class more often. Bye!!!!
