Turned E (∃) is a symbol based upon the letter E. It is used to represent existential quantification in predicate logic. When it appears in a formula together with a predicate variable, they are referred to as an existential quantifier.
In Unicode the symbol is encoded U+2203 ∃ There exists (HTML ∃ · ∃).
There also exists a Latin script letter U+018E Ǝ Latin capital letter reversed E (HTML Ǝ) used in some African languages.
References
Turned E Wikipedia(Text) CC BY-SA