Pot bottom to insert in stove eye?

[JShapiro]

Can anyone tell me what the style of cookware is called that has a bump on the bottom to be inserted in a cook stove eye? I'm looking for ways to find them online—I have an old cookstove with eyes and am considering getting some pots/pans to fit them. Here's an example of an old kettle:

https://imgur.com/a/CE4LdYS

 

[Doug D.]

Pit bottom. See https://www.castironcollector.com/shapes.php

 

[JShapiro]

Pit bottom. See https://www.castironcollector.com/shapes.php

Thank you so much!