Echo

The echoes that Slugcat meets are the spiritual remnants of Rain World's previous civilized race, the Ancients, who appear to slugcat as large black beings with golden scales and long snouts, appearing to be sitting in a fetal position. They are forever stuck between this world and transcendence. Six echoes can be met throughout Slugcat's journey. Their names and locations are as follows:
 * Nineteen Spades, Endless Reflection, found at the highest point in the Chimney Canopy, near the gate to the Sky Islands.
 * Six Grains Of Gravel, Mountains Abound, found atop The Wall region of The Exterior shortly after the player exits from the chamber of Five Pebbles.
 * Four Needles Under Plentiful Leaves, found in a grotto underneath the eastern entrance to the Shaded Citadel.
 * A Bell, Eighteen Amber Beads, found in the Farm Arrays high above a patch of Worm Grass, near the entrance from the Outskirts.
 * Two Sprouts, Twelve Brackets, found in the Subterranean region as one enters from the Farm Arrays, in a cave to the right.
 * Droplets Upon Five Large Droplets, found high up in the Sky Islands, above the orange lizard infested tunnel near the gate to the Farm Arrays.

Gameplay
Echoes are non-hostile and will attempt to speak with the slugcat if they have the mark of communication, teleporting them back to their previous shelter once they are finished. They will also attempt to raise slugcat's maximum karma tier up to a maximum of 10, and the player will awaken at their new maximum karma level. If the player meets an echo before meeting Five Pebbles, their karma will increase by two on the first echo encounter and one every next encounter until they achieve level 10. Echoes will always be found in a specific location, but will not be there every time. The player must go to the room the echo appears at to trigger a flash of dark blue light, and then return at least a cycle later with either their maximum karma (or for some echoes one below the maximum) to get the echo to appear. The presence of an echo is very obvious, as even at a distance the area will grow darker and unique music will play. As slugcat gets close, flecks of gold will start raining down and blue light will be seen slowly moving across the screen. Enemies will typically not be found during this time, and most creatures other than slugcat that get too close will fall limp to the ground. If the player has already been given the gift of communication by Five Pebbles, the echo will give a brief monologue to the player, otherwise the player will be teleported back to the shelter almost immediately upon finding them.

Encountering an Echo
In order to encounter most of the Echoes, the player must visit the area where they reside twice. The first time, when the player gets near, they will see a blue flash of light, and nothing more. If they visit the area on a following cycle with a high enough karma level (either their maximum or the karma level just below their maximum), they will find the pacifying blue effect described above and eventually meet the echo. This is not the case for Six Grains of Gravel, Mountains Abound or Two Sprouts, Twelve Brackets, who can both be found on their first visit.

Nineteen Spades, Endless Reflection
Behold this empty husk of a land...

Populated only by storms, ruins and abominations. It wasn't always thus.

I was once the Count of 2 living blocks, esteemed by my peers. I had progeny!

From within my vessel of flesh, I would perch upon this spot to observe the rising of the sun.

Corporeal matters seem so distant now. Most have forgotten this place, but I remain.

Perhaps I reminisce because I cannot go. Perhaps I cannot go because memory traps me here.

Six Grains Of Gravel, Mountains Abound
We can feel your presence, little creature.

Your attunement has become... much closer to ours.

The mark you received is an unimaginable gift.

The struggle, the cycles...

It can all fade, like a morning mist beneath the glory of the sun.

We found a way.

Four Needles Under Plentiful Leaves
You have no name.

I once had! I was embalmed, adorned, readied for the journey.

So proud. There was jubilation! My name was sung, loud and clear.

Did they know? That I didn't quite leave, didn't quite stay?

Should I be ashamed? That I linger here, where my memories are kept?

Should I be ashamed that I now envy your flesh prison?

A Bell, Eighteen Amber Beads
Strange...

Something still draws me here. Even after all this time.

The weather is so different now, but the fields...

I do not need eyes to know that the grasses still sway gently in the winds.

To have grasped at the boundless infinites of the cosmic void...

Yet here I am contemplating these same fields as I once did, talking to some sort of rodent.

Two Sprouts, Twelve Brackets
A little beast!

But not as dim as the rest, perhaps?

So down into the depths you go as many others before you, drawn to the void again and again, an endless drip drip drip.

Much like these tunnels and caves that amuse me so. The bones of forgotten civilizations, heaped like so many sticks.

Did they dig too deep, or not deep enough?

Fools. We were right to drill straight through them!

Droplets Upon Five Large Droplets
Do you hear it, little one?

The buzzing in the air?

The endless chatter of a thousand thousand voices, long dead?

They are gone, and yet they speak. Neither here nor there.

Does that seem familiar? Yes, it is quite amusing for a being in my predicament!

Trivia
It is possible to complete the game without going to Five Pebbles by talking to four of the Echoes, each raising your maximum karma slightly. Reaching the maximum karma level this way earns the Pilgrimage achievement.
 * Some echoes do not have to be triggered to be found as the hunter. The hunter only has to visit their area with a high karma level.
 * Echoes are the result of a being with many vices attempting to break the cycle of reincarnation using void fluid, and becoming stuck between this world and the next. Looks to the Moon notes that this is especially the case for those who are too arrogant or egotistical.
 * Scavengers or some other sentient beings seem to have been aware of the Echoes at some point, as a "ghost" symbol appears near many of the Echo locations.
 * Scavengers are not pacified by echoes.