  We demonstrate the occurrence of permanent spikes using the
Lemaitre-Tolman-Bondi models, chosen because the solutions are exact and can be
analyzed by qualitative dynamical systems methods. Three examples are given and
illustrated numerically. The third example demonstrates that spikes can form
directly in the matter density, as opposed to indirectly in previous studies of
spikes in the Kasner regime. Spikes provide an alternative general relativistic
mechanism for generating exceptionally large structures observed in the
Universe.
