The thermostat (which has the housing built into it) has two outlets on it, one obviously for the radiator hose. The hose pictured is the thermostat bypass hose, which goes to the smaller outlet on the thermostat. From the best that I can tell, the Nissan part # is
21306-4W020. The part diagrams make it difficult to locate, so this is how I'm coming up with that number: the hose goes from the thermostat to the coolant pipe under the intake manifold, however the part catalog shoes the hose under the oil cooler parts diagram.
If we go to part diagram 210 for the thermostat and water pump, we can look at the thermostat, part code 21200 (Note: copy and paste whole link rather than click on hyperlink):
https://www.nissanpartsdeal.com/parts-l ... &PNC=21010
We can see the radiator hose outlet on the thermostat has an arrow pointing to section 214, where we can find the radiator hose. The smaller outlet on the thermostat has an arrow pointing to section 213, which has the hoses for the oil cooler (Note: copy and past whole link rather than just click on hyperlink):
https://www.nissanpartsdeal.com/parts-l ... &PNC=21305
As we look at section 213, we see the hose labeled as part code 21308+D, which has an end with an arrow pointing to section 210 and is the only hose showing a reference to section 210 (the thermostat/water pump section). Hose 21308+D comes up as part number 21306-4W020. So, I would have to assume that it's the thermostat bypass hose despite what the oil cooler diagram suggests. It also seems to have a similar shape as the OP's picture. Of course, the only way to be 100% sure would be to get the hose and compare it to the original.