Where does “sea blossom” come from?

sea blossom (English) comes from English Blossom, from Middle English blosme, from Old English blōstma, from Proto-Germanic blōsmaz, from Proto-Germanic blōstaz, from Proto-Indo-European bʰleh₃-s-, from Proto-Indo-European bʰleh₃-, from Proto-Indo-European bʰel-.

Ancestry of “sea blossom”, step by step

sea blossom traces back through two separate lines of ancestry.

via English Blossom

StepLanguageWordMeaning
1EnglishBlossomA flower, especially one indicating that a fruit tree is fruiting; a mass of such flowers
2Middle EnglishblosmeA flower or blossom; An outstanding or...
3Old Englishblōstmaflower, blossom
4Proto-GermanicblōsmazAlternative form of *blōstmô
5Proto-Germanicblōstazblossoming
6Proto-Indo-Europeanbʰleh₃-s-bloom, flower
7Proto-Indo-Europeanbʰleh₃-bloom, flower
8Proto-Indo-Europeanbʰel-to sound; to speak, roar, bark; shiny, white; to...
9Proto-Indo-Europeanbʰōl-

via English sea

StepLanguageWordMeaning
1EnglishseaA large body of salt water; A lake, especially if...
2Middle Englishseesea, ocean; A body of water, a lake; seat, chair
3Old Englishsea, lake
4Proto-West Germanicsaiwisea
5Proto-Germanicsaiwizsea, ocean
6Proto-Germanicsīhwanąto filter
7Proto-Indo-Europeanseykʷ-to moisten; to filter
8Proto-Indo-Europeansey-to be wet; dribble; run; to stretch one's arm;...
Every word from Proto-Indo-European bʰōl-Every word from Proto-Indo-European bʰel-Every word from Proto-Indo-European bʰleh₃-