Ark Black Pearls are needed for crafting high-end items in Ark Survival Evolved, luckily on the Lost Island, they are not very hard to get, once you know where they are. Squid and the occasional trilobite will produce black pearls, but on the Lost Island map it is far easier to pick them up in their black shell, off of the floor of the ocean or even ponds.
The two spots to get black pearls that are the easiest are located on the main island. The first is at the bottom of a pond by the geysers. Just swim down to the bottom and pick them. There is nothing dangerous in the pond, only around it. The pond is shallow, and you won't need scuba gear or some swimming dino, but flippers are very handy. The second is just inside a cave and you only have to deal with a handful of nasty creatures. There are more caves with black pearls, but I don’t think caves are great for resource harvesting due to all the dangers, so I will leave those out.
Pond near the geysers -Best black pearl location on the Lost Island map.
Not far from the entrance to the cave that contains the Artifact of the Strong. Sometimes called the Aberration Cave it is also a great place to get gems on the Lost Island.
All the other good locations that I have found are at the bottom of the ocean floor. Here are some select good locations for seafloor Lost Island black pearls. For these black pearls, you will need a scuba tank, and a swimming dino, with good weight, since black pearls are so heavy, unlike silica pearls.
Select Ocean Locations
82.5 16.1 Shipwreck