Treyarmus is a hydrogen-helium gas giant with a strong magnetic field, making it a popular discharge point for freighters working on the Anansi-Ishtar shipping route.
It is popular enough, in fact, that quarian ships can often be found loitering in orbit, selling the freighter crews cheap refreshments, salvage, and odd craftworks assembled by their children. There are no ships in orbit at present, however.
Treyarmus is too small to be a "hydrogen-helium gas giant" (William Hubbard, The New Solar System 4th ed, 1999; p. 194). It is more likely a dense "ice giant" like Neptune or Gliese 436 b.