Bryozoans are a group of minute aquatic animals just barely visible to the naked eye. Their fossils are among the most common in the world, especially in parts of North America where their broken skeletons can form entire limestone beds.
There are nearly 6,000 living species and over 15,000 extinct species dating back at least 480 million years. These species vary in appearance and behavior but, generally speaking, bryozoan colonies consist of many semi-autonomous, hermaphroditic clones called zooids that build coral-like structures of calcium carbonate to live within.
This fossil is a branch of one such structure. If you look closely, you may notice small pits in the surface. Each pit was once home to a single zooid. They were attached to the structure and survived by feeding on microscopic organisms floating by.
After the Permian/Triassic event, when 96% of marine life went extinct, enough bryozoans survived to recover in the Mesozoic and become as successful as before.