You need a Fish & Wildlife permit (~$200 regardless of order size) for all marine ornamental livestock. Anything requiring a CITES permit (all LPS and SPS corals, seahorses, clams) is nearly impossible to import because most vendors will not be willing or able to do the CITES application for you (seller has to do it) unless your order is very large and they have done the process before. Plus you usally have to pay customs duties for buying outside of Canada. In all honesty, it is easier to order from the Philippines (or ANYWHERE else) than the USA because the country of origin just needs a simple CITES permit where importing from the USA requires a RE-export permit since the livestock didn't originate in the USA. They don't recognize aquacultured fish or corals as originating in the USA or Canada either btw.
You can ignore all this and just drive through the border hoping for the best, but that is called smuggling and can result in huge fines, jail time, and a criminal record.
Back in the 90's I used to drive across the border (we lived near a very small border crossing) and brought all sorts of stuff back all the time. I did notice later in the 90's they started asking more questions and I was more likely to have to pay customs duties.