Sparkling Sponge Spicules

Tiny sponge spicules.
Solvin Zankl / Nikon Small World

These sparkling sponge spicules are microscopic needle-like structures that many sponges use as a structural skeleton and as a defense against predators. When such a sponge dies, it crumbles into tiny spicules, which become part of the sand in coral reefs. This image, taken at 10x zoom, was named an Image of Distinction in the 2013 Nikon Small World photomicrography competition.