Makes an excellent, low-maintenance gift for anyone! These terrariums are self-contained micro ecosystems, and really need very little care. They should present with a bit of moisture/condensation most of the time, and if you notice that it is dry, it's time to open it up, add a little water, and simply replace the lid. Leaves that die will fall down, and decompose, becoming nutrients for other plants. Moss will die, revive, and cycle through different stages of it's life. Volunteer plants will often show up, usually ferns.
These are available in store only, and cannot be shipped. These will often contain springtails, and sometimes in the larger vessels, isopods. These are part of the ecosystem and are placed in it to keep it clean and healthy.