Learn how to say Porphyra correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word laver:
an edible seaweed with thin sheet-like fronds of a reddish-purple and green colour which becomes black when dry. Laver typically grows on exposed shores, but in Japan it is cultivated in estuaries.
Porphyra umbilicaulis, division Rhodophyta
late Old English (as the name of a water plant mentioned by Pliny), from Latin. The current sense dates from the early 17th century