Secu-Tanks, also known as Tank Bots were the strongest type of guard at the Boltaire Museum. Their gun fired powerful grenades that made a small explosion when they hit Clank or hit the ground. It is a very bad choice to destroy them without weapons.
Secu tank

A Secu-Tank with it's back turned.

Secu tank and watchmen

A Secu-Tank and Watchmen firing at Clank.