This is still my favorite online exploration of what might be fossiliferous matter on Mars: http://aix1.uottawa.ca/~weinberg/mars/

The filaments aren't covered to any great extent, but trilobites, pillbugs, and fishing lures are. Michael Davidson approaches his materials both seriously and humorously -- with admirable skepticism and wild speculation. Given the immense amount of knowledge we have yet to learn, both seem appropos.

If there is or has been life at or below the surface of Mars, more than likely we have already seen -- but so far have mostly failed to recognize -- abundant evidence of it.

If there isn't any life at or below the surface, we need to ask why there is so much mimicry of biological formations and processes on Mars.

It is to wonder...

Cheers, BRFelix