Pinkish Submarines
My youngest is a little over a year old and hasn’t started talking yet. Instead he seems to aspire to be a submarine when he grows up. He communicates via improvised sonar.
If he can’t see me or his brother he’ll call out “Ah!” several times in various directions. He’ll keep doing this until one of us responds with “Ah!” Then he goes back to whatever he was doing content in knowing where everyone is.