Players should be wary of their handling of the eggs, as they take damage when attacked by enemies or impact certain obstacles. The egg gauge in the lower right-hand corner of the screen begins to crack, as does the egg Billy wields. When the egg takes enough damage, it is destroyed and no bonus comes from it. Eggs can also be 'lost', i.e. put into positions or situations that the player cannot retrieve them from. In such cases, the egg will disappear from its position after several seconds of inactivity and will 'respawn' in its nest of origin, but will lose any maturity the player earned for it. Some characters from other games appear in certain eggs, such as Sonic the Hedgehog or NiGHTS. These specific eggs are marked with the Sonic Team logo on them.