Or, she pushes out eggs for customization and if it hatches inside you get lots of points.
Thus, you get the choice of how you want to deal with the eggs.
Doesn't need to be a monster, when it thematically wouldn't make sense.
How about you have a groper tentacle (style thing) slowly emerge from the hole, and then disappear below. So it would then need a backend as well, but you'd then be reusing an existing mesh/texture, just used in a different manner. Maybe a little smaller or several escaping at once.