Uni is sea urchin roe. When fresh, it is oily and rich that is not firm but rather paste like.
How To Prepare Uni For Sushi/Sashimi

Uni is sea urchin roe. When fresh, it is oily and rich that is not firm but rather paste like.
Ikura is salmon roe. Each egg is shaped like a small orange sphere, glistening and filled with salty liquid.
Herring roe is sold removed from the herring, generally salted to preserve it.
Similar to a sweetened omelette, tamagoyaki can be prepared as nigiri sushi or included as one of the many side dishes to a meal. It is also a common addition to bento boxes.
Kuruma ebi is a prawn. It should be skewered from the belly to the end and rinsed before boiling in salty water.
Ika (cuttlefish) is best very fresh, when the texture is not so rubbery. The tentacles, called geso, can also be used.
Octopus is always served boiled, as the flesh is hard to chew when raw. Only the tentacles of the tako are eaten.
The flesh of akagai, or ark shell, is pinky orange.
The pale beigey yellow flesh of scallop is exquisite.
Abalone is known as awabi in Japanese. It is a sea snail, and when fresh, has a great texture. When it’s a little old but still edible, you will find that it will become rubbery, so make sure it’s as fresh as possible!