According to Monroe, only an immortal can get rid of Loki completely, so it canb e assumed that the trolls might be immortal.
At the end of the same episode, Thor summons a few new ones to banish Loki again.
As cited by Jasmine, the Trelleckians are one in just a handful of blue trolls and have red hair and that there haven't been any blue troll sightings in a long time. They have pointy ears and misplaced or missing teeth. They carry hammers and are dressed similar to depictions of Scandinavian mythology.
- Ah-mah says that there haven't been any blue troll sightings in a long time but later in a season 2 episode "Dog Show Afternoon", June hires a few Securitos trolls herself, who happen to be blue.