Thusa was a female humanoid of an alien species whose members reproduced and/or resurrected themselves by touching someone else to create an infantile clone of themselves.
In 2381, after the original Thusa was killed by the Grafflax, she immediately transferred her essence into Lt. jg Sam Rutherford, and thus created her clone. For days and being trapped inside a cave, both Rutherford and Dr. T'Ana each took a turn looking after Baby Thusa while the other searched for a way out. She, Rutherford, and T'Ana were eventually led to safety by the Grafflax. (LD: "Caves")