Octagrabber, also referred to as Roomba or Optimus Prime is a robot that lives on the deck of OCISLY. The robot first appeared in March 2017 and is used to stabilize and secure boosters to the droneship.
The robot has 4 arms and tracks. After landing, the robot leaves its blast-protected garage and drives underneath the booster. It uses four arms to then attach itself to the booster, securing it.
In the past, recovery crews had to board the droneship and attach additional support struts and chains that were then welded to the deck. Octagrabber allows for quicker recovery.
For more information on Octagrabber, take a look at this page on ElonX.net