What’s this gasket?

I was doing some work under the hood tonight, and found this on the ground under the front of the truck. Any idea where it goes?

 

what was the work and what other work has been done recently.

 

I replaced the spark plugs and engine air filter, though the piece was closer to the front than where I was working.

 

maybe under coils?
It looks like a spark plug tube grommet but those don't just fall out.
Have you replaced them on another car lately?

 

Nope. Just the Taco, and I’m certain the garage floor was clear before starting the job. I did have the coils resting in a tray above the fan. Are there circular gaskets on them?

 

Yes check all your coils to see if one is missing

 

Thanks Gmak- hopefully it’s one on the passenger side. Thanks for the help!

 

I’ll defer to someone with hands-on experience, but I did not find them listed in the parts diagram.
That just means Toyota doesn’t sell them separate, but would be part of an assembly (coil pack?). Usually they will show them, but bracket, so I suspect there isn’t a separate boot.

EDIT: I see someone else answered in the interim.
Thanks @Gmak621 for giving reference.

 

GMak was spot on- it was a gasket for the coil, which must have slid off during the job. Unfortunately, it was from the driver’s side, so I had to redo the toughest coil. Much easier the second time around, though.

Thanks again @Gmak621

 

No prob. Cheers