Some places serve rice in a football/quenelle/shell-like shaped scoop/mold/mould for food presentation. It's consistent at many teriyaki places so I suspect it's something you can purchase.
I've searched for the following terms:
quenelle, in conjunction with
mould but haven't had any luck.
(Click images for larger view)
The closest I've found is a "Deep Boat Petit Four Mould", but the bottom is flat instead of a dome.
Edit: This is used to mold sticky rice, ideally they would have the 'shell like' ridges running longitudinally/lengthwise). All of these teriyaki pictures are from the Seattle area.
Update (2016-06-19): Found the mold in use in Japan. It's commonly used in omurice.
(From this video)