In some versions, however, Mari Morgans carried kidnapped sailors to underwater palaces of mother-of-pearl and crystal, and married them. The morgens, eternally young, are also blamed for heavy flooding that destroys crops or villages.
The passage describes a mythical being named Mari Morgans who is responsible for kidnapping sailors, taking them to underwater palaces made of mother-of-pearl and crystal, and marrying them.  In some versions, she is also blamed for causing floods that damage crops or villages.