Glass melon bead 
Date: 1 century BC to 1 century AD
Roman 

Spherical opaque white glass melon bead with 8 ribs. 
Intact, very good condition.

Max diameter: 20 mm
Height: 14 mm

For similar published beads in museum's collection see:

-Alexeeva E.M. Antichniye busi severnogo prichernomoriya, Academy of Science, Moscow, 1978, table 33: 48