Examining under a a light microscope, there are characteristics that would allow for identification of the cell as an animal cell rather than a plant cell. Some common things to look for are summarized in table below:
Characteristics Plant Cell Animal Cell
Cell shape Rectangular Irregular
Outer covering With cell wall No cell wall but has cell membrane
Vacuoles One and large Many and small
Chloroplast Green pigments Absent
Centriole Green organelles Barrel-like structure