What is the purpose of the 2 Bat Coffins? The Tiny Bat Coffin and Special Bat Coffin

Question

I looted a Tiny Bat Coffin from a Gloom Maw. It seems like a very rare drop since my team finished charming Gloom Maws (2500 kills) and only looted 1. When used, it displays the message "Na Nanna Na Nanna Na Nanna!" and then is on cool down for 1 hour. If used on cooldown, it can't be used on another item meaning crosshairs don't appear when right clicking the item. An important difference is that the Tiny Bat Coffin can be sold to NPC Yasir for 3650 gp but the Special Bat Coffin can't be sold to an NPC. 

You see a tiny bat coffin. It weighs 6.30 oz.

Sprite when item is on cooldown where the eyes are closed and a strap appears across the coffin. 

Questions: 

What is the purpose of a tiny bat coffin? 

Is it at all related to the unknown new achievements? 

Is a tiny bat coffin at all related to the Special Bat Coffin? 

How is the Special Bat Coffin obtained? 

Does it have any special purpose other than being the green version of the tiny bat coffin? 

Important information: Tibiawiki.com.br is conducting some research into this item as well. Source: https://www.tibiawiki.com.br/wiki/Tiny_Bat_Coffin

Comments

As curiosity in the files of the game there is a version of used (With that ''stripe'' on it) one in green color too.

Answer 1

The special bat coffin is obtained through the quest door in the Norcferatu dungeons.

Info on how to obtain it can be found here;

https://www.reddit.com/r/TibiaMMO/comments/1mnpxpf/bloody_tusks_questline_continuation/

and

https://www.tibiaqa.com/37392/how-do-i-access-the-sealed-door-in-norcferatu-dungeons

The text seems to be related to the batman theme song-

https://www.youtube.com/watch?v=EtoMN_xi-AM

They just appear to be rare vanity items at the moment.

However, since there are two coffins and two new unknown achievements, it is possible they are related and more info will be available in the future.

Comments

The CD starts to go off in you backpack? Or do you need to put it in a house?

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Needs to be carried while logged in or sitting on the floor of a house.