What is the yellow goop in toilet tank?

Hi -- I'm brand new to plumbing and to this board, so I apologize if this is a stupid question, but I googled around and checked my Sunset plumbing book and can't find an answer: Inside the toilet tank, around the base of the valve seat where it connects to the inside bottom of the tank, there's a ring of yellow-white goop that looks kind of like toothpaste. Clearly some kind of sealant, but what is it? It's soft; when I touch it, a bright yellow smear comes off on my fingers. Can/should I scrape this stuff out and replace it when I clean the valve seat and replace the flapper, which is why I'm rooting around in the tank in the first place? The toilet is 59 years old; I don't think the flapper/assembly is quite that old, but it pre-dates my time in the house (12 years). Sometime in the next year I hope to replace the whole toilet, but I'm hoping to wait till I'm ready to put in a new floor at the same time, so right now I'm looking to stop it from running/leaking and keep it going a bit longer. Any and all advice welcome -- thanks!

I don't think the goo will be in a book.
After 59 years, I don't even want to know what it might be.

It makes me wonder if maybe the flapper had been leaking in the past, and someone maybe used some type of vasoline or lubricant to try and get it to seal a little better? Honestly, I have no clue, Im just throwing ideas out there.

I think your idea to clean off the old stuff, whatever it is, and redo the flapper and fill valve should work fine until you can get your remodeling project finished. My guess is the "stuff" is something Billy Mays sold on TV (not available in stores)

Thanks!

Well, I'm glad to know I'm not the only one mystified by this stuff. Thanks everyone for your suggestions.

I love old houses, but they are full of surprises!