Looks like some high quality maguro there, no? But biting into it won't send you to tuna heaven. Because this particular bite of sushi is actually molded sugar sold as a kit. Here's how they made it. [Reddit]
If you guys are wondering how the roe was made, it's a common technique in molecular gastronomy called spherification. You can make spheres out of practically anything. You just need to mix the liquid you are using with sodium alginate (derived from seaweed). Then you drop it in a solution of calcium chloride dissolved in water.