Montereina nobilis MacFarland, 1905 Anisodoris nobilis (MacFarland, 1905) Diaulula nobilis (MacFarland, 1905) Peltodoris nobilis, commonly called the sea lemon, false sea lemon, or the noble dorid, is a species of colorful sea slug, a dorid nudibranch, a shell-less marine gastropod mollusk in the family Discodorididae.

This animal gives off a pleasant citrus smell when it is handled, and this (along with its yellow coloration) is what is responsible for the common name 'sea lemon'.

Its diet includes Mycale adhaerens, the purple scallop sponge.

This species occurs in the Eastern Pacific Ocean from Alaska to Baja California.

This animal can grow to be as large as 200 mm, or nearly 8 inches in length.