Hn... [Yuusei gains a slightly worried expression as he keeps reading.]

It says that they were created by the science of an ancient civilization out of clay, but no one has been able to identify exactly what kind of energy it is...although according to you, Aiapec...

[Silence.] Its species have been 'active' for thousands of years... [He turns the page and raises an eyebrow.] They can breed and evolve, despite being artificially created, apparently.