Abstract
This chapter commences with an account on the Zillo Beasts. The reawakening of extinct species, or "de‐extinction," has gained massive popular appeal. The chapter explains some facts before delving into the philosophical debate over de‐extinction. Philosophers sometimes use far‐fetched examples to answer the questions that are left after we agree on all the facts. These “thought experiments” are meant to show us what we really believe. What makes a duck a duck, a mammoth a mammoth, or a Zillo Beast a Zillo Beast? This is called the species problem, and it is one of the oldest in the philosophy of biology. Essentialism is the view that permits us to say that the Zillo Beast's clone would be a member of the Zillo Beast species. The New Essentialists argue that essentialism can be compatible with natural selection if one looks beyond organisms' traits for species essences.