The Red Bubblimp is a member of the Bubblimp Family featured in Hey! Pikmin. They look like a red simple-celled organism. Acording to Captain Olimar, all the red Bubblimp encountered in Hey! Pikmin are newborns.
The Red Bubblimp appears by drip out from the ceiling, they are harmless and die if they bump into Olimar or his Pikmin. They can however knock them by bursting near them, which can push them near hazards or more dangerous creatures.
Hey! Pikmin Log
"These newborns are so fragile that one touch will kill them. They grow by absorbing water on the ceilings. They are sturdy as a raindrop and every bit as dangerous. Er... Hmm..."