Under what conditions do Ender Pearls despawn?

I use long-term Ender Pearl stasis on a server that I frequent as a sort of fast travel. A chamber has been failing on me lately, leading to a rather lengthy trek each time.

This leads to the question. Under what precise conditions will an ender pearl disappear without teleporting the thrower? The player being offline is an obvious one - are there any others?

Solution 1:

The pearl despawns on owner's death (unless the gamerule doImmediateRespawns is set to true) or if it's triggered (collides with a solid surface), regardless of whether the owner can be teleported or not: in particular, the owner may be in other dimension (no cross-dimension teleportation allowed), logged out or dead.