Standard models of SNR evolution indicate that after the shock has swept-up
an amount of mass significantly larger the SN ejecta, the ejecta should be
well-mixed with the swept-up ISM and difficult to observe. Aschenbach
et.al. (1995) suggested that the \"bullet-like$quot; features seen near
the outer rim of the Vela SNR are large fragments of ejecta which have
recently caught up to and passed through the shock. Follow-up observations
on the Vela fragments A (Miyata et.al. 2001) and D (Plucinsky et.al. 2001
and Katsuda et.al. 2005) indicated significantly enhanced abundances
consistent with the ejecta hypothesis. It is somewhat surprising to find
such large fragments of ejecta in a SNR which is approximately 18,000 yr
old. Simulations by Wang and Chevalier (2002) indicate that such fragments
can only survive if they are rather massive and have a density contrast
which is ~1000 times that of the ambient medium. We will review the
properties of the apparent fragments in Vela and review the possible
existence of such fragments in other SNRs.