The Growing Maw (3.5e Feat)
From D&D Wiki
The Growing Maw [Racial]
Your studies and mental effort pay off, and you become even more Beholder-like, as beneath the eye on your back, a large maw begins to grow.
Prerequisite: B'er'den, Fifth level in any class, Beholder Bloodline
Benefit: You develop a large mouth on your back which gives you a Bite (2d4) attack. However, like the eye above it, the maw can only be opened when you are Curled.