The generic name refers to Phoronis (better known as Io), a Greek mythological character sometimes conflated with Isis.

[7] Horseshoe worms are not very sensitive to environmental conditions and are therefore considered to be both eurythermic and euryhaline animals.

While they are not very sensitive, there are some factors that can impact their distribution such as current strength (as they are filter feeders), the result of asexual reproduction, predation in the area, and local fauna which they may have to compete with.

However, horseshoe worms have a relatively global distribution as they can be found in the Atlantic, Pacific, and Indian oceans.

[8] The horseshoe worms live in tubes that are fully imbedded in the soil and are formed during digging or boring.

These thin films are composed of fibers from the worms that form nets that make up these tubes.

[8][10][11] Through moving water over the tentacles of the lophophore, they act as an organ for gas exchange and allow oxygen into the blood as it passes through.

Recently, it was discovered that some species even exhibit viviparity, where the embryos are incubated in the coelom of their mother's tube and the "hatch" to produce feeding actinotroch larvae.

[13] When they are full grown, these worms typically have thin but long bodies that can grow up to 50 cm.

The small fertilized eggs, numbering up to 500, are then released through spawning into the water column where the larvae develop over a period of 3 weeks before settling to change into the adult stage.