Umbran Resting Place

The Umbran Resting Places, commonly referred to as Treasure Chests, are the tombs of the Umbra Witches that are scattered around Vigrid, Noatun, Fimbulventr, Paradiso, and Inferno. They are sealed stone coffins that the strongest of the deceased witches were buried in after they departed from the world. No one can open the caskets without proper knowledge of the Witches' magic; even during the Witch Hunts, the caskets remained sealed. The Lumen Sage Seal of the Sun was placed upon the Resting Places as a magical counterweight after the Hunts finished. If the Witches' power were ever to return, they will not escape their tombs due to the seal.

In both games, the Umbran Resting Places act as treasure boxes that house various items for collection, ranging from Broken Witch Hearts and Moon Pearls, to Golden LP record fragments that can be exchanged for weapons, lollipops and Halos.

Witch Graves Within The City
From Antonio's Notebook:

''Vigrid is littered with the legacies of an ancient age. Amongst these are the stone coffins used to bury departed witches. Along with their fellow overseers of history, the Lumen Sages, the Umbra Witches used their incredible power to repel any intrusion upon Vigrid.''

Under these auspices, the witches abode by the terms of their netherwordly contracts, and upon parting with the physical world, the strongest of the witches were deified 

''as guardians, and buried in stone coffins throughout the town. These stone coffins were sealed tight, and it was said that only those with the knowledge of a witches’ magic could open them. Even during the witch hunts, when the coffins were subjected to attempted demolition, not a single soul was able to peer into the contents within. ''

''According to one theory, the contract with their demon master stipulates that upon leaving this earth, a witch’s soul nor body can remain. Umbran burial customs were developed for that very reason. The women would bury their loved ones in treasured stone coffins to lessen the pain of those destined for Inferno, even if the effect was slight. ''

''Today, unable to break the magic seal upon the coffins, the Lumen Sage Seal of the Sun has been placed upon the sarcophagi as a counter-weight. If by chance the power of witches were to return to this world, they would be prevented from opening their coffins due to the seal. This is a clear indicator of the sort of persecution these women were subjected to during the witch hunts. ''

''While the whereabouts of the witch’s tombs is outlined above, the location of the tombs for the Lumen Sages remains unknown. According to remaining records, they had taken up final resting places with the Umbra in the secluded region known as the Crescent and Sunrise Valleys. It is said the Lumen Sages, who conducted their duties not in the darkness but the light, rest peacefully in the valley after departing from this world. ''

''Finally, there are rumours that somewhere in Vigrid, research is underway to extract the Spirit Energy from departed witches. It seems that the fate of the Umbra Witch and Lumen Sage has yet to be truly decided.''

Divine Retribution
From The Journal's Echoes:

''If you're going to spit in the face of God, you're probably going to incur some of his wrath. That's just common sense to me. Still, I can't help but feel a little sorry when I hear the level of divine retribution some of these witches get dealt.''

''One case I witnessed was particularly bad. The type of punishment that never gets better, hurting for all eternity, like a curse. An Umbra Witch had the Resting Place that carried her remains shattered into pieces and her soul flung into a rift in time and space, never to be saved again. Just thinking about what this witch must've done to get dealt a hand like that drives me almost insane with curiosity. I'd kill for the chance to sit down and chat with the Lumen Sages that did it to her.''

Yet, judging from the witches I know, you could expel them to the ends of the universe and they'd still find a way back.

Bayonetta
In the first game, the Umbran Resting Places are scattered throughout both Vigrid and Paradiso and must be broken open with a Wicked Weave attack, in order to break the seal and obtain the item inside. If an item such as a Witch Heart or Moon Pearl has already been acquired from the chest, then it will give an Arcade Bullet the next time it is broken open. The chests come in particular variations depending on the stage of the game.

The most common kind are the casket-like chests, ones that appear to be a tomb for a Witch but with a heavy gold Sage inspired seal on the top, surrounded by gold chain. In Paradiso, the entire chest appears golden and has a heavenly motif, making it appear much grander than a Witch's casket and also implying these are the resting places of dead Lumen Sages. Onboard the Valkyrie in Chapter XII, the chests act as power units for the plane and are wired into the craft's structure.

Bayonetta 2
The Umbran Resting Places return in the sequel and function in the same way as the first game with a similar appearance as well. They also appear in a brand new variation that are related to the Remembrance of Time, having been sealed so heavily they are banished, from reality as an ultimately cruel final punishment to them.

These chests appear as interdimensional oddities, seeming out of phase with the rest of the level. Approaching one of these chests prompts Bayonetta to collect the scattered pieces of the chest in a specific time limit before being able to break it open. Instead of the golden seal on top of the usual Resting Places, these chests have a blue, angular- themed seal based around the imagery of Aesir, in contrast with the Resting Places, in the previous game. Interestingly, one way to locate them is with the Chain Chomp equipped as it will detect and attack any nearby Umbran Resting Place.

Locations
See this guide for the location of each chest. (locations for Bayonetta 2 are Work in Progress)

Trivia

 * In The Eyes Of Bayonetta artbook, concept designer, Ikumi Nakamura's concept art depicts that a Witch's body was planned to be present in the casket. The corpse would be bound by the hands and feet as part of the burial process for the Witches with the very same ribbon that Bayonetta wears in the first game.