Subwassertang

A Fern Disguised as a Liverwort

Thought to be a liverwort at first, it is actually a gametophyte of a fern; no species name has been given as of this writing.

See
Süßwassertang: A Fern Disguised as a Liverwort

Li et. al. 2009 Identifying a mysterious aquatic fern gametophyte