The Heart Scallop (Perpetuus opercularis) was a land mollusk, a soft-shelled bivalve of the Forannis Triad.
The Heart Scallop begins its life as an airborne polyp, anchoring itself to a likely cliff-face or large tree after a short adolescence in the planet's jet stream. After anchoring, the animal survives by pumping vast amounts of air through its alimentary canal, straining micro-organisms from the air for sustenance.
It grew to weight upwards of 300 pounds, noted for the astounding strength of its single muscle. It is so named because of its continual, regular, and powerful muscular contraction-expansion cycle.
Some of the slaves on the Forannis Triad used the scallops to aid in their work: they would carefully trim the shell of a large scallop, and, by connecting it to a series of levers and rods, transform the Heart Scallop's continual bellows action into usable power.
Jehane Golitle, looking for some method of constructing a flying machine that could combine the versatility of a bird with the size of an artificial aircraft, discovered the secret she sought in the Heart Scallop looking in the Imperial Scientific Archives.
She petitioned the emperor Neweh to allow the entire group to travel to the Forannis Triad and began intensive experimentation, culminating in 7580 BG with the test flight of the first true ornithopter, which is actually a domesticated, specially-bred Heart Scallop connected to a series of electrical leads.