Before you get too horrified, let me clarify: they were squid babies, and the shopping cart was underwater. 
I learned about the discovery from NewsTalkZB, which reports that at an aquarium in Wellington, 

30 squid are expected to hatch tonight. Discovery programme manager Julian Hodge says the squid were found in a discarded shopping trolley during a clean-up of Wellington Harbour three weeks ago.

Nearshore squid normally lay their eggs on surfaces like rocks or sand or shells, but they will just as happily lay on manmade surfaces like pier pilings, beer bottles, and . . . shopping carts.

You can't make this stuff up.