Bulb or Grenade?
At first glance, this object looks a bit like a bulb or maybe even a salt shaker without any holes, but there’s more than meets the eye. According to the OP, it was in their research lab for years and no one knew what it was, not even their former PI.
The scientists of the internet however know exactly what it is – a fire extinguisher grenade from the early 1900s. It turns out some were filled with water while others had a chemical concoction and when they were thrown, these bulb grenades would help suppress a fire by removing the oxygen. We wonder if this one would still work…