In New England, we have square hot dog rolls ( the ONLY kind that one should use for a lobster roll !), but we also have the rounded ones, here in Ct. too. From N.Y. down, they only have the rounded ones.
Yes, square ( they really are rectangular ) hot dog buns, slathered with butter and then put on a griddle, filled with lobster salad. It’s a standard summer dish in New England and Maine is known for them. They’re DELICIOUS! :-)