Me getting slaughtered by Marauder fleet (and he's got bigger ones)!.. What the heck is a Boomer, I think I need one of those, is that the amoeba thing I can research?
Yeah, ouch. While not as powerful as Fallen Empires or the endgame-crisis, Marauder fleets are still no joke. Losing that system with the ruined Ringworld is gonna smart.
If you own the Distant Stars DLC, you can get the "Lost Amoeba" event as the result of the "Movement in the Clouds" research anomaly. Once you've researched the anomaly, you'll get the option to "adopt" it into your empire (as long as you're not playing as a destroyer empire (Fanatic Purifier, Devouring Swarm, Determined Exterminator)), and it will join your fleet.
After a certain period of time (180 days?), the amoeba matures into an adult, with a power rating of 400-600 (depending on your tech level). At this point, you get the option to name it, with "Boomer" being one of the options.
Several decades later, the amoeba matures even further, reaching 100 years of age. She'll typically have a power rating of 5-6k, comparable to a battleship.
I try not to throw my amoeba (I usually name her "Bubbles") into a fight unless I'm desperate, but she's definitely nice to have around.