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sea walnut,common name for some members of the phylum CtenophoraCtenophora
, a small phylum of exclusively marine, invertebrate animals, commonly known as comb jellies. Because they are so delicate that specimens are difficult to collect, little was known about them until the advent of blue-water scuba and submersible collecting.
..... Click the link for more information. , whose members are also called comb jellies.