The Alley Cats

The Sea-Monkeys are three brine shrimps that appear in The Secret Life of Pets. They are members of The Flushed Pets, a group of abandoned pets led by the evil white rabbit Snowball.

Bio
They were part of the brand Sea-Monkeys, being created since cysts. They were "flushed" when their owner noticed that they didn't look like the ones of the ad.

Trivia

 * Sea-Monkeys is a real-life brand name for brine shrimp. The brand mainly consists in hatching and taking care of an Artemia nyo.
 * In real-life male brine shrimps have a second pair of enlarged clasping antennae, but in the film one of the Sea-Monkeys (which is male) seems to lack of them.