What is the best use for 'captivating treasure' and 'searing enigma'?

[Linus Sex Tips]

Its been hanging in bag for ages now and I think its a bit of a waste to give it to the university..

[BlackUmbrellas]

Captivating Treasures can be turned into Heirlooms at your Townhouse or Manor and allow your next character to cash them in for money.

[Elitewrecker PT]

Searing enigmas can be used to buy Dread Surmises for 9 enigmas, which are sold at Irem for 10 enigmas.

[SMILEDOZER]

Sell them treasures. If you have more than 1 use one of them for Heirlooms. Or just mo money.

[txh0881]

Turn them into Heirlooms. Then sell them all on a future captain for an easy retirement, or quality ship.

[Akninirith]

Interesting usage is that you can actually improve spy networks in the Khanate or Port Carnelian with them on occasion; with a little luck and processing, you can churn out a fair quantity of Vital Intelligence by way of your networks. Also, your spy networks can be used for several purposes (like bringing London into power), and can come into play even more heavily if you're a Zubmariner.

[Citizen Joe]

Searing enigmas are mostly useful for quest requrements, and can also be used to acquire the Dread Surmise from certain locations.

Treasures are useful to sell or alternatively convert into heirlooms in case you die

[YetiChow]

Searing Enigmas can also be traded for Doomed Monster Hunters at Codex; if you use the Enigmas <-> Surmises trade to multiply your Enigmas this effectively makes the most expensive ammo in the game free. If you need to hunt down Mt Nomad (which is basically end-game anyway), or some other horrible Zeemonster from the DLC, then this might be a handy option.