Rock: Rock is one of the earliest characters created, in 2014 rather than in 2015. Rock originally had a much wider body and smaller pair of legs. He originally wore pink shorts but was later changed to overalls as his design was inspired by a background character in Adventure Time. Rock is paired with Blockster and they both work as miners an lumberjacks. Rock originally had a human name. His name was Rocky. Surprising I know.
Sponge: Sponge is created for one specific joke. He is created supposedly to be the Animated Diversity version of SpongeBob Squarepants, but this idea was later dropped for obvious reasons. Unlike SpongeBob who is a sea creature, Sponge has a thin green layer of scouring pad behind him, which states that he is a kitchen sponge.
Teardrop: Teardrop is one of the members of the Droplet Nonuplet, along with Waterdrop, Acid Drop, Drooldrop, Peedrop, Oildrop, Inkdrop, Blooddrop, and Rainddrop. Teardrop is created for one specific joke, it’s that she’s constantly in a state of sadness throughout her existence due to her species. She always feels down and pessimistic, and even goes hard on herself simply for existing. She is often times seen with Waterdrop as an emotional support companion.