Here are two groups of four words based on their characteristics:
Group 1: Animals
- Cat
- Lion
- Ram
- Bull
Group 2: Fantasy/Other Themes
- Grinch
- Turtle (from "Teenage Mutant Ninja Turtles" or can be associated with fantasy)
- Pop (can refer to "pop culture" or "pop music," which can include fantasy elements)
- Crab
Alternatively, if you want to focus purely on living creatures without including some themes:
Group 1: Land Animals
- Cat
- Lion
- Ram
- Bull
Group 2: Sea Creatures and Others
- Turtle
- Crab
- Pop (as in 'pop' culture rather than animal association)
- Grinch (a fantasy character)
Let me know if you would like them grouped differently!