What is the source of food for Profollias downhoki?

It seems you might be referring to the Greenland shark, also known as Somniosus microcephalus. This shark is a deep-sea fish and doesn't have a common name like "Profollias downhoki".

Here's what we know about the Greenland shark's diet:

* Opportunistic feeders: They are opportunistic feeders, meaning they eat whatever is available in their environment.

* Diet: Their diet includes:

* Fish: Cod, halibut, skate, and other fish species.

* Marine mammals: Seals, walruses, and even polar bears.

* Carrion: They are known to scavenge on dead animals, including whales.

They are slow-moving sharks that primarily hunt in the deep waters of the North Atlantic Ocean. Their diet is highly dependent on what they can find and catch, including dead animals.