baby cacti?

I have found more of these tiny prickly things sprouting in the depths of my boston fern:

There's six or seven of them now. Funny because you think a fern needs damp soil, and cactus totally dry. The fern is looking crowded. I ought to divide and repot it, clean out excess dry crowns. But several times in the past have killed all the divisions, so reluctant to upend it now.