The Organic Turret is a scrapped Duke Nukem 3D enemy.
Sprites and horribly-broken code for an unused enemy called the Organic Turret can be found in the game’s files. Its organic look suggests that it would fit into the alien-infested areas in Episodes 2, 3 and 4.
Functioning code for this enemy can be found in v0.99 and can be hacked into a level. It behaves much like the regular Turret, but instead fires the Enforcer’s spit projectile. Given how easy it is to kill and how easily its projectiles can be dodged, it was probably scrapped because it served no purpose.
This enemy was nearly completely scrapped in the final game. Its sprites have been used for new enemies by modders, but none of these reflect how the Organic Turret was supposed to behave.