Eggs have always been fascinating to me. This is largely due to their "forbidden fruit" status caused by my faulty immune system. As an adolescent I was allergic to egg yolks (and chocolate, which is another whole story). And, as any cook can tell you, egg yolk is in many recipes. Dessert food especially--just about every cake and pastry contains this taboo ingredient. My only options were angel food cake (made with egg whites only) and certain prepackaged yolk-less substitutes, like Egg Beaters, for scrambled eggs. Both of these were okay, but I was anxious to try the delicious-looking doughnuts, birthday cakes, etc., that my peers regularly ate. Alas, my allergy was no joke--not being able to breathe was a powerful deterrent.
Fortunately, this all changed during puberty. This period of innumerable chemical changes sometimes has the side effect of causing people to gain or lose allergies. Luckily for me, my food allergies disappeared, and I've been making up for lost time ever since. I've mostly had the regular chicken eggs, of course, but I have been able to try a few unusual ones, like salmon, flying fish, lumpfish, and quail.
Salmons' sense of smell is incredible--they are able to make the arduous trek from the ocean all the way back to the fresh water rivers or lakes where they were born, to mate, based on "scent memory." I've had their eggs in Japanese restaurants, as sushi. The eggs are about as big as peas, and are orange in color. They're delicious--they're nicely (but not overly) salty, and they pop in your mouth in a pleasing way. I highly recommend them.
Flying fish are wonderfully weird creatures. What an awesome defense strategy they have. A predator is chasing a tasty-looking fish, and then, Wham!--it leaves the water and is gone. "Flying" is a bit of an exaggeration, as it's really a glide, but their trips are pretty impressive. they average about 160 feet, and reach heights of 20 feet above the water, and speeds of 43 miles per hour. One Japanese team filmed one flying for a record 45 seconds! Their eggs are tiny, about the size of large grains of sand. Naturally orange, they're sometimes colored black (using squid ink), or green (using wasabi). They're very good. I would rank them below salmon, as they're slightly blander, but still well worth it. They're much more common, too, as many sushi rolls use them as a garnish, coating the outsides of the rolls with them. In a typical sushi meal it's probably hard not to eat some.
Finally, the last exotic egg I've had in a sushi restaurant is quail. Befitting the birds' size, their eggs are probably about one-third as big as a chicken egg. I had them raw (I think), atop a bed of rice, enclosed by seaweed. They're very good as well. Although, like the salmon eggs, sometimes hard to find on an average sushi menu. Quail eggs are pretty common fare in many parts of the world. In Venezuela and Columbia hard boiled ones top off hamburgers and hot dogs. The Vietnamese boil them as bar snacks. In the Philippines they soft boil them and then fry them. In South Korea and Indonesia, they're a typical street vendor offering.
Lumpfish eggs I see occasionally in grocery stores. And I encourage readers to look up photos of this animal, as it's bizarre and accurately-named. They're roundish, fat, and sometimes have gross wart-like growths all over their skin. They're also called lumpsuckers, as their modified fins are adhesive, allowing them to stick to rocks and other objects. Their flesh is a common item in Scandinavian cuisine. Anyway, I was excited to try this roe, as they were billed as "caviar," and were correspondingly slightly expensive (as memory serves, it was about $6-8 for a tiny jar). The upshot was, unfortunately, that they were terrible. Plain or on crackers they were like eating a mouthful of salt. I couldn't even finish the minuscule serving--totally revolting.
I'll end with mentioning some unusual eggs on my "to try" list. First off is caviar, the actual sturgeon kind seen in James Bond movies and the like. Since genuine caviar from the Caspian and Black Seas is about $2500 a pound (!), though, I'll have to sell way more books to eventually hope to afford this. More realistically, I'd like to sample some ostrich and emu eggs. Ostrich eggs, obviously, are giant (20 times heavier than a chicken egg), and reportedly make a nice, gargantuan omelet. Emu eggs are nearly as big, supposedly good, yet have a weird appearance, resembling avocados. With the increase in ostrich and emu farms in the U.S. in the past few decades (for meat and hides), maybe I'll have a chance to try their eggs in the near future.