Was changing the spark plugs in my 1987 pickup and noticed the ceramic from one of the plugs was missing. Could this be fatal? What kind of damage could happed from such an incident? Ideas welcome....

 

Get a cheap scope and take a look in the cylinder but it’s probably gone.

 

I'd be switching to NGK plugs.
whatever, if any damage is already done. If it's running good, new plugs and consider yourself lucky.

 

Go back to OEM plugs. I use Denso W16ERX-U. Never have an issue, runs very well, last forever, and are cheap. Why guess with others. I pull them every Spring to clean and re-gap them. Run them 5 years (~60K plus miles) and replace them just to be safe, although they are still running well.

 

Bosch are notoriously bad sparkplugs for Toyotas. They’ve never done well or held up. I’m also not fond of plugs with screw terminals. I prefer solid.
ND or NGK basic resistor plug will never disappoint.

 

After it broke off it probably whoshed right out the exhaust port, weaving its way through the cat, rattling on the sides of the muffler, and then popped out to be a new windshield divot in some poor FJ somewhere.

I'd not give it another thought.