and molly was chased by a horrible thing which raced sideways while blowing bubbles:and
Then we have molly, poor molly, who's getting chased by a bubble-blowing crab. The speaker doesn't tell us it's a crab, but we can put two and two together and figure out what this sideways running creature is.
Before we get that major clue, though, the ambiguity in "horrible thing" leaves line 7 open for interpretation in terms of the countless "horrible" things a kid might encounter at the beach. Shark? Pirate? This guy?
And since the speaker doesn't state outright that this is a crab, we can even experience molly's terror in the same way she does, not knowing why this creature is chasing her. Our speaker just tells us that it looks pretty weird running sideways and blowing bubbles (not with gum) and so maybe we're meant to feel the mystery and potential danger of the sea even more.
We certainly hear it here. Where did our rhyme go? These lines are the first that don't even come close to rhyming.
We guess that's appropriate for this scary scenario. There are all sorts of weird things lurking beneath those waters that we don't know all that much about, and that scary looking crab symbolizes that mystery in just the right way.
By now we're also catching a bit of the allegory that the speaker is relating to us through this poem. Each scenario described so far relates to an idea about a real life circumstance. The one we see here, with unknown and scary creatures, makes us think about those same scenarios a kid—or anyone— might encounter in real life. The unknown always has an element of scariness, right?
That's the kind of idea the speaker is working with here through the allegory of the scary crab.
From a big-picture perspective, these beach scenes points out how there are always plenty of opportunities to encounter strange, beautiful, comforting, or scary things in life. Check out more about the big, bad, and beautiful world in our "Themes" section.