Lore
Mimics take the achievement of opening a chest and turn it into a test. This first mimic in Sen's Fortress sits askew in the room, its chain uncoiled, and faintly heaves up and down as it breathes. More than that, it makes every future chest a possible threat.
Mimics have gangly arms that shoot out of the chest to grab their prey. Similarly, their long legs emerge from underneath to raise them so they tower over the victim. A mimic will gnaw on its captured prey with teeth composed of boney fingers and thrust the victim into the belly of the chest. It does all this while its tongue waggles out of its mouth, flailing in an upsetting way.
The mimic can be triggered without grabbing the Chosen Undead by hitting the chest before opening it, or it can be pacified with Lloyd's Talisman. Slaying it or pacifying it will produce the item the mimic was holding as a reward.
Design Works Interview
Theories
Mimics are From Oolacile
Sources
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To be honest, I don't think that the Mimics' teeth are finger at all.
While they may seem like teeth here:https://trazobit.files.wordpress.com/2012/11/gus-mukin03.jpg
They don't look like teeth at all here: http://assets.vg247.com/current//2016/04/dark_souls_3_mimic.jpg
Maybe other see fingers… but I really don't see them.
You have a heart of gold. Don't let them take it from you…
Please see this image for explanation. Please click for a bigger view of it.
Hope that helps.
PS. Please do not post Dark Souls 3 related content to the Dark Souls 1 and 2 sections.
I still don't see it. The "fingers" are too metallic and sharp ingame for me.
Don't panic though ^^
The image says DS3 but it's obviously DS1.
You have a heart of gold. Don't let them take it from you…