The small grain-like bodies inside cells that produce proteins are called ribosomes.

Here's why:

* Ribosomes are the protein factories of the cell. They read the genetic code from messenger RNA (mRNA) and use it to assemble amino acids into proteins.

* They are small and granular. Their size is typically measured in nanometers, making them appear as tiny dots under a microscope.

* They are found in all living organisms. Ribosomes are essential for all forms of life and are present in both prokaryotic and eukaryotic cells.

Let me know if you have any other questions!