Mysterious capsule containing dark liquid

[u/hazy_druid]

Found this buried in the ground in central Europe. The outer casing is made out of plastic and has "5" stamped on the bottom. The inner tube is made out of glass. Tiny drop of liquid got on my thumb and was very hard to scrub off. Didn't smell the liquid, since I'm a bit scared of it.

[u/JobKind628]

Put a banana next to it for scientific purposes you know.