Scientists exploring a deep ocean basin in search of species isolated for millions of years found marine life believed to be previously undiscovered, including a tentacled orange worm -- "We don't know what it is," scientists said -- and an unusual black jellyfish near the sea floor.

Project leader Larry Madin said Tuesday that U.S. and Philippine scientists collected about 100 different specimens in a search in the Celebes Sea, which is at the heart of the "coral triangle" bordered by the Philippines, Malaysia and Indonesia.

"This is probably the center where many of the species evolved and spread to other parts of the ocean, so it's going back to the source in many ways," Madin said.

The deepest part of the Celebes Sea is 16,500 feet. The team -- which involved the Woods Hole Oceanographic Institution and National Geographic Magazine in cooperation with the Philippine government -- was able to explore to a depth of about 9,100 feet using a remotely operated camera. Madin said it would take "a few more weeks" of research to determine whether the species are newly discovered.