Tyrellia is an inhabited planet located within the Federation's sphere of influence, known for being only one of three such planets to lack a magnetic pole and one of only seven without any kind of atmosphere. Tyrellia is also the homeworld of the Tyrellians.
Starfleet officer Calvin Hutchinson was once stationed on Tyrellia during the mid-24th century. (TNG: "Starship Mine")
- Most likely the Tyrellians developed and live underground.
- Data noted that there were five Tyrellians stationed aboard the USS Enterprise-D. This may indicate that the planet might be a member of the Federation.