Inheriting an inherited IRA from a spouse

If I inherit the following three IRAs from my spouse:

• Traditional IRA (no RMD yet taken/required; does that matter?)
• Roth IRA
• Inherited IRA (spouse inherited from parent)

what can I do with the inherited IRA?

Several sources (e.g. Fidelity, IRS) indicate that I can treat the Traditional and Roth IRAs as my own and roll them into my existing IRAs. However, I can’t find any direct answers about options for the inherited IRA. Does it need to be closed immediately? Can I slowly draw it down over some number of years (if so, based on my spouse’s date of death? their parent’s date of death? my life expectancy?)? Or since it comes from my spouse can I treat it as my own?