Plagiomnium cf. Affine
Common Name: Pearl Moss
This is an interesting moss with round leaflets that form on the end of each frond. It 's an extremely slow growing plant that's hard to find due to it's rarity.
Propagation is the same as with any other moss; just split the main plant into smaller portions and it'll grow.
As mentioned, this plant does well in low light, and in a low Co2 level. It can grow submerged or emersed.