The planula is a small, free-living larva, and is diploblastic with two layers: the endoderm and ectoderm with an additional mesoglea.

Further, the ectoderm has mucous gland cells for secretory purposes, support, and sense along with cnidocytes with nematocysts in the posterior end.

[2] The planula remain free-living for a short time, after which they settle onto hard substrate and then complete metamorphosis to become its adult form.

[4] During metamorphosis, the species destroys most of its endoderm and ectoderm tissues as it undergoes a massive reorganization of its body.

[4] The planulae demonstrates cephalization with concentration of neurons and sensory cells in a dome shape at the anterior end.

[6] Clava multicornis reproduces sexually as the larvae are fertilized in the gonophores on an adult female.

[7] As planulae crawl along the substrate with ciliary gliding, they move with their anterior end forward.

[2] Additionally, these planulae exhibit positive phototactic behavior (moving towards the light source).

They have become a model for determining effects of retinoic acid (used to regulate physiological processes in chordates) on this phototropic behavior.

[11] The species tends to live in sheltered areas on algae away from shores because the planulae cannot settle when there is too much wave action.

They can only feed efficiently in lesser currents because their tentacles become deformed from intense waves, causing their size to diminish.

Further, when the planula larvae develop, they settle close to the bottom and middle of the algae since they are fragile against waves.

One known species is the larvae of Pycnogonum litorale, a sea spider who lives as an ectoparasite on C. multicornis either in its stolon or hydrocaulus.

The similarities that placed them in the family include having stolons growing off of its skeleton and a variation in the formation of polyps.