Ectoplasm Valheim 1.0.20
Ectoplasm is a crafting material that stacks to 50 in Valheim.
“A restless essence of a once living thing...”
Ectoplasm is a material. The in-game description calls it "A restless essence of a once living thing..."
Each piece weighs 2, and you can carry up to 50 in a single stack. It can be teleported, so you can take it through a portal with you.
Other material items
Acorns, 
Amber, 
Amber Pearl, 
Ancient Bark, 
Ancient Coin, 
Ancient Metal, 
Ashlands Gourmet Bowl, 
Ashwood, 
Asksvin Bladder, 
Asksvin Hide, 
Asksvin Neck, 
Asksvin Pelvis.