Viruses? Algae? Mold?
Nope -- just grapefruit, lemon, and orange peel. I was making marmalade and the little dots revealed fascinated me and I had to get a picture. So I taped the peels to a sunny window.
Then I had to get a shot of the peeled fruit . . . and then, of course, I made the marmalade.
Such a pleasant occupation on a coolish, fallish day. I did no canning this summer (except for one run of pepper jelly,) putting into the freezer what little of our garden produce the critters didn't get and we didn't eat fresh.
The familiar rituals -- assembling the jars, rings, and lids, pulling out the funnel and the jar lifter, preparing the fruit, measuring the sugar, waiting for the boil, timing the various steps, and, of course, that rewarding ping! that says the jars have sealed.-- are all the more pleasurable on a quiet, unhurried Sunday afternoon.