I find the trick with Bolbitis (and all Ferns) is to not bury the Rhizome and give it plenty of current. I've been keeping Bolbitis for 6 years or so and I've learned a lot over the years. I always tie mine to bits of wood and find it will grower bigger in current. If the fronds are not swaying slightly in the current it will tend to stay quite small. I've just uploaded pics of mine here;
I guess it does grow in an unusual way, it just seems to get thicker and thicker sending rhizomes every which way.