Spaghetti flavored with Alaska pollock roe. たらこスパゲッティ。
Tarako resembles mentaiko; the difference is that in the case of mentaiko the roe has been chili-flavored, while tarako is only salted. So tarako has a softer flavor.
It may seem extravagant to use fish eggs for spaghetti and from an Italian viewpoint it is certainly unorthodox. But foods like pizza and spaghetti, sandwiches, and of course now also sushi ("California rolls") have always been subject to fantasy arrangements when crossing cultural borders, and there is nothing wrong with that. Moreover, tarako spaghetti is in one word: delicious!
By the way, mentaiko spaghetti also exists.
Tarako is also used as a filling for a popular kind of onigiri (rice balls).