Several out-of-nowhere topics of conversation at the table in the last few days:
M2: Did you know that an octopus is made from bacteria?
(We determined that he was thinking of pearls.)
This led to a heated discussion about pearls forming in clams.
MG: Do you know what a walrus eats?
Again this worked its way around to pearls forming in clams.
M2: I know of a planet called Earth.
MG: We are all on the planet Earth!
MG: We all have 3 types of teeth! (Followed by a mini-lecture on what each type of tooth is good for.)