Cacti can rarely develop very strange, abnormal growth patterns, either monstrose (random, deformed growth) or cristate (crested tip) growth patterns. The photograph below shows a crested Saguaro (Carnegiea gigantea).

Next is a crested Chainfruit Cholla (Opuntia fulgida) shown below.

Below is a crested Cane Cholla (Opuntia spinosior) that appears to have normal stems emerging from the abnormal growth.