We present a new fast active contour for images in 3D microscopy. We introduce a fully parametric design that relies on exponential B-spline bases and allows us to impose a sphere-like topology. The proposed 3D snake can approximate blob-like objects with good accuracy. The optimization process is remarkably fast. Our technique yields successful segmentation results even for a challenging data set where object contours are not well defined. This happens because our parametric approach allows us to favor prior shapes. This work comes with a companion software that allows extensive interactions between the end-user and our snakes through the intuitive manipulation of the few control points that fully characterize them.