[Moonman62]

We should assume these “fossils” are of non-biological origin until there is stronger evidence otherwise.

[BroJoeK]

Moonman62: "We should assume these 'fossils' are of non-biological origin until there is stronger evidence otherwise."

Here is a photo, this article said they are about 1.6 inches high:

Stromatolite fossils have been found in many places from many different time periods, including the relatively recent past.