Fact 1: Adult tunicates are barrel-shaped. Fact 2: Tunicates differ strongly in appearance between the adult and larva. Given the two facts above, what differ strongly in appearance and are barrel shaped?

Available choices:
[I] bears.
[II] barnacles.
[III] abdomens.
[IV] oxen.
[V] Leptospirosis.
[VI] cacti.
[VII] burrs.
[VIII] tunicates.
Answer:
[VIII]