What is the object these Romans are carrying?

Factual Questions
1

In this engraving in the Arch of Titus, the Romans are depicted carrying a menorah from the Temple of Jerusalem in the year 70, but what is the other object being carried? It looks like an ancient movie camera. What is it?

http://www.artlex.com/ArtLex/a/images/arch_titus.relief.lg.jpg

2

Romans sometimes carried a rigid “banner” with company symbol or “SPQR” (“Senatus PopulusQue Romanus” – “The Senate and People of Rome”). This looks like one of those.
Here are some modern copies:

http://www.legionxxiv.org/signum/

3

An SPQR guidon?

EDIT: Or, what CalMeacham said.