There are a number of hats in the lab. We see a fez, a top hat, a toque, a baseball cap, a porkpie, and two more hats that are just offscreen.

Moving along we see the two remaining hats are some sort of cowboy hat and a bowler with a slight indentation at top.

Dobbsey: How did all these hats get here?

Brainley: Well, it's their mating season, so they're starting to swarm.

Dobbsey: oh.

Dobbsey: ...oh.

Dobbsey backs away abruptly. Brainley tilts slightly in puzzlement.