Common liverwort (Marchantia polymorpha) Is a subtropical ground covering plant with forked branches that will grow to 4 inches long. It does not produce flowers nor seeds. Considered a weed in gardens and lawns, it forms a dense carpet over the ground and reproduces by spores. It is fire tolerant and has been useful in woodland restoration projects to help deter ground erosion.
I personally would remove it, robs nutrients and clogs up your soil.