Club Moss 'Frosty Fern'
This is a Selaginella kraussiana, aka 'Frosty Fern', also known as Club Moss. Oddly enough this plant is neither a moss or a fern. This little section of the plant world is what they call a fern ally. Fern allies are a diverse group of seedless vascular plants that reproduce by shedding spores for metagenesis (a type of reproductive cycle in plants also sometimes called alternation of generations). They do exhibit many of the same care traits as their true fern brethren.
Your Club Moss loves a low to medium indirect light, damp soil and cool humidity. They do particularly well in temperate terrariums or by a kitchen sink where it may get frequent splashes.