There are many living things that only have four letters, off the top of my head in one minute I came up with the following (only one is plural since you said "a living thing")...
ants, aunt, bird, bush, calf, crow, dame, fish, frog, goat, tree
sear
gold dust
Envy Is A 4-Letter Word
4 letter word for drum is "Dhol".
Salt is a 4 letter word for seasoning.
cell
a toad
sear
sell, sway
lion, lamp, list
gold dust
seed
4 letter thing that ends with m is SPAM.
Envy Is A 4-Letter Word
4 letter word for drum is "Dhol".
4 letter word for final
Salt is a 4 letter word for seasoning.