I find it easier to remember the contrary case: you only use the apostrophe when you mean to say “it is.” In this special case, you don’t have to think about possession at all.

Eleftrons.

I understand the temptation for snark, but if you’re going to snark, I suggest that “here is how I googled it for you” is a better response, wherein you explain the terms you chose and how you selected the most pertinent result.

Definitely more work, but even if the OP is infuriating, there are people who will find the answer in the future, and who would benefit from the explanation of something that might be obvious to us but not them.