What is this?

Picture contributed by Ed Braun.

These elongated sacs are asci containing ascospores of the fungus Sordaria fimicola. The radiating asci have been squeezed out of a fruiting structure called a perithecium (not visible). The neck of the perithecium is phototropic, thus it bends toward light. Following this movement, S. fimicola will often shoot its ascospores a short distance toward the light.

This fungus normally inhabits dung but is also commonly found in introductory mycology laboratories.