Among other, more doable things, I got a cook's credo quest (5th tier) to study a dark heart. I've never even gotten one of these things, though apparently you can get them rarely by butchering creatures, much like a grotesque tumor. Information on any of the following questions is welcome:
* Can all creatures yield dark hearts, or only larger ones? Could I get one from a rabbit or squirrel?
* Do you get a chance at a dark heart from cleaning, or butchering, or both?
* Does anyone know approximately what the actual chance is of getting one? 1/1000? 1/1000,000?
* Currently I'm hunting a lot of lower-tier animals in the field, cleaning then butchering them, and throwing out the meat. Is there a better way of farming them? Is it plausible that I can find one if I just keep it up, or would it be better to just abandon this quest? (I'm in 5th tier, so any quests I get now are going to be fairly difficult)
* Does anyone have one that they can spare? I'm willing to trade, but I don't have a huge amount of capital for a curio this rare, so it's admittedly kind of a long shot. I could probably do a large quantity of low-q tar, at least.