One of the unknown animals dredged from the ocean depths near the Philippines was a species of sponge which was found to contain numerous branching worms inside its cavities.

In 1879, one of these worms was formally described by the Scottish marine biologist William Carmichael McIntosh, who named it Syllis ramosa.

[3] The heads of the two individual S. ramosa brought to the surface by the Challenger were located in the bases of glass sponges of the class Hexactinellida.

The gut in this part of the animal is absorbed, the muscles are rearranged to facilitate swimming and the stolon becomes a storage receptacle for the eggs or sperm.

When the breeding period arrives, the stolon becomes detached and swims to the surface of the sea, in a process termed "epitoky".