sea lettuce

Short definition from Wiktionary

Noun

1. 1
   Any of several edible seaweeds of the genus Ulva.
2. 2
   Similar seaweed species of other genera
3. 3
   Similar seaweed species of other genera: Monostroma spp., also known as the slender sea lettuce, a kind of algae.
4. 4
   Scaevola taccada, also known as the beach cabbage, a terrestrial flowering plant species that is native to coastal regions of the Indo-Pacific.
5. 5
   Dudleya caespitosa, also known as the sand lettuce, a terrestrial flowering plant species that is endemic to coastal areas of California