Lifesaver
The Lifesaver is a mechanic in the Splatoon 2 mode Salmon Run, serving as a reference point to shoot ink and resuscitate fallen inklings.
Description
The Lifesavers are translucent rings with white bands, normally attached to the Inklings' backs, serving as their Ink Tanks during Salmon Run. When full, the translucent parts appear in the player's ink color. A small light on the rightmost ring of the Lifesaver indicates if you have enough ink for a Splat Bomb the same way Ink Tanks have a light on the top.
When a player is splatted during Salmon run, they will reappear shortly thereafter as a controllable Lifesaver with a 
Grizzco Flag and an Inkling ghost jumping around inside it. They will appear at the point where they were splatted, or (if splatted in midair, on a moving platform, or by falling in the water) on the last piece of solid ground the player stood on. If a Lifesaver moves or falls into the water, it will fall apart and reappear back on solid ground after another short time.
In this form, the player moves very slowly, cannot attack or swim in ink, and their jumping height is severely decreased. However, they are also invulnerable, can pass through all types of Salmonids and are unaffected by enemy ink. The player's "This Way!" Signal is replaced with a "Help!" Signal.
If the player had a Golden Egg when splatted, it will stay with them in Lifesaver form and cannot be lost (except by waiting until the wave ends). If an empty Lifesaver approaches a Golden Egg, it will be picked up, just like when not in this form.
Shooting at a Lifesaver with any main weapon or special weapon will cause the player to revive and give them 4 seconds of mercy invincibility, where the Inkling will flash and be invulnerable. Some weaker main weapons may require more than one hit to revive the player. A 
Splat Bomb exploding next to a Lifesaver will revive it, and if one hits a Lifesaver directly, it will explode immediately, similar to hitting the Rainmaker barrier or the canopy of an enemy Brella.
Gallery
-
An Inkling with a Lifesaver on the back
-
A lifesaver
