It is thought that excess lipids in the cell are packaged into lipid droplets in the endoplasmic reticulum. Explain why lipid droplets bare surrounded by a phospholipid monolayer and not a phospholipid bilayer, like other vesicles that bud from the endoplasmic reticulum.

Lipid Droplets are cell structures that store fat in the form of neutral lipids, these droplets are hydrophobic (do not interact with water) which is why they are surrounded by a phospholipid monolayer, with the hydrophobic phospholipid tails oriented toward the neutral lipid core

This is different from most other cellular organelles, which have aqueous lumens and are therefore, surrounded by phospholipid bilayers.