Distinguishing features of the Grannan included skin cuffs that allowed them to retract their fingers and toes, respiratory sacs that allowed the breathing of methanogen and loose eye creases.
Grannan naming conventions placed the surname before the personal name.
A small community of Grannan lived on Polneye until the whole colony was wiped out by the Yevethan Purge, leaving Plat Mallar as the sole survivor.