Here's what you should know about the nucleolus:

* Function: The nucleolus is the site of ribosome biogenesis. It produces ribosomal RNA (rRNA) and assembles ribosomes, which are essential for protein synthesis.

* Appearance: It appears as a dense, spherical structure within the nucleus.

* Location: The nucleolus is not a membrane-bound organelle, but rather a region within the nucleus where rRNA genes are concentrated and ribosomal subunits are assembled.

Let me know if you have any other questions.