What is "grypania"

Grypania is an early, tube-shaped fossil from the Proterozoic eon. The organism could have been a giant bacterium or bacterial colony, but because of its size (over one centimeter) and consistent form, is more likely to have been a eukaryotic alga. The oldest probable Grypania fossils date to about 2.1 billion years ago, and the youngest extended into the Mesoproterozoic era. Grypania reproduced asexually .