<div class="squirtle">
  <div class="tail"></div>
  <div class="body">
    <div class="stomach"></div>
    <div class="shell"></div>
  </div>
  <div class="head">
    <div class="eye"></div>
    <div class="eye"></div>
    <div class="mouth"></div>
  </div>
  <div class="leg back"></div>
  <div class="leg"></div>
  <div class="arm back"></div>
  <div class="arm"></div>
</div>

html { box-sizing: border-box; }
*, *::before, *::after { box-sizing: inherit; }

body { font-size: 100%; } /* Controls Size */

.squirtle {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 20em;
  height: 20em;
  margin: -10em;
  //transform: translate(-50%,-50%);
  animation: bounce 250ms infinite linear alternate;
}

.squirtle::after {
  content: '';
  position: absolute;
  z-index: -10;
  bottom: 0;
  left: 50%;
  width: 60%;
  height: 20%;
  margin-left: -30%;
  //transform: translateX(-50%);
  background-color: rgba(0,0,0,0.05);
  border-radius: 50%;
  animation: bounce 250ms infinite linear alternate-reverse;
}

.body {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 6em;
  height: 6em;
  margin: 4em 0 0 -1em;
  transform: translate(-50%,-50%);
  overflow: hidden;
  background-color: #fe9;
  border: 0.375em solid #555;
  border-radius: 10% 10% 50% 50% / 50%;
}

.body::before,
.body::after {
  content: '';
  position: absolute;
  z-index: 1;
  top: 2.25em;
  left: -1em;
  width: 1.25em;
  height: 1.5em;
  transform: rotate(55deg);
  background-color: #fe9;
  border: 0.25em solid #555;
  border-radius: 10%;
}

.body::after {
  z-index: 0;
  top: 4.825em;
  left: 1.375em;
  height: 1.25em;
  transform: skewX(10deg) rotate(40deg);
  box-shadow:
    0.375em -3.375em #fe9,
    0.125em -3.0625em #555;
}

.stomach {
  position: absolute;
  bottom: 3.25em;
  left: -1.125em;
  width: 115%;
  height: 100%;
  border: 0.25em solid transparent;
  border-bottom-color: #555;
  border-radius: 50%;
  box-shadow:
    0 1.25em #fe9,
    0 1.5em #555;
}

.stomach::before {
  content: '';
  position: absolute;
  bottom: -4.125em;
  left: 2.25em;
  width: 40%;
  height: 100%;
  transform: rotate(-10deg);
  border: 0.25em solid transparent;
  border-left-color: #555;
  border-radius: 50%;
}

.shell {
  position: absolute;
  top: 0;
  left: 0.25em;
  z-index: 1;
  width: 100%;
  height: 115%;
  border-radius: 10% 10% 50% 50% / 50%;
  box-shadow:
    inset -0.5em 0 #953,
    inset -1em 0 #a63,
    inset -1.25em 0 #555,
    inset -1.75em 0 #fff,
    inset -2em 0 #555;
}

.tail {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 4.5em;
  height: 5.5em;
  margin: 0.25em 0 0 -0.5em;
  transform-origin: 2.5em 100%;
  //transform: translate(-50%,-50%);
  background-color: #6bc;
  border: 0.325em solid #555;
  border-radius: 50%;
  animation: bounce2 250ms infinite linear alternate;
}

.tail::before,
.tail::after {
  content: '';
  position: absolute;
  top: -2em;
  left: 2.25em;
  width: 5em;
  height: 5.5em;
  background-color: inherit;
  border: 0.325em solid #555;
  border-left-color: transparent;
  border-radius: 50%;
}

.tail::after {
  top: 0.375em;
  left: 2.625em;
  width: 2.5em;
  height: 2.75em;
  transform: translateX(1%);
  background-color: transparent;
  border: 0.325em solid #555;
  border-right-color: transparent;
  border-bottom-color: transparent;
}

.head {
  position: absolute;
  z-index: 1;
  top: 50%;
  left: 50%;
  width: 10em;
  height: 10em;
  margin: -8.25em 0 0 -5.5em;
  //transform: translate(-50%,-50%);
  background-color: #7cd;
  border: 0.325em solid #555;
  border-radius: 50%;
  animation: bounce2 250ms infinite linear alternate;
}

.head::before {
  content: '';
  position: absolute;
  bottom: -0.0625em;
  right: 1.625em;
  width: 8.25em;
  height: 5em;
  transform: rotate(10deg);
  background-color: inherit;
  border-radius: 50%;
  box-shadow:
    0 0 0 0.325em #555;
}

.head::after {
  content: '';
  position: absolute;
  width: 100%;
  height: 100%;
  background-color: inherit;
  border-radius: 50%;
  box-shadow: inset -0.5em 0.25em #6bc;
}

.eye {
  position: absolute;
  z-index: 1;
  top: 5em;
  left: 4em;
  width: 2em;
  height: 2.825em;
  overflow: hidden;
  background-color: #555;
  border: 0.1875em solid #555;
  border-radius: 50% / 60% 60% 40% 40%;
  box-shadow: inset 0 -0.375em #a63;
}

.eye::before {
  content: '';
  position: absolute;
  top: 0.375em;
  right: 0.25em;
  width: 30%;
  height: 30%;
  background-color: #fff;
  border-radius: 50%;
}

.eye:first-child {
  top: 4em;
  left: 0.5em;
  width: 1.5em;
  height: 2.25em;
  border: 0.125em solid #555;
  box-shadow: inset 0 -0.25em #a63;
}

.mouth {
  position: absolute;
  z-index: 1;
  bottom: 0.75em;
  left: 2em;
  width: 1.125em;
  height: 1.75em;
  background-color: #fcc;
  border: 0.125em solid #555;
  border-radius: 50%;
  box-shadow:
    inset 0 1.125em 0 -0.0625em #f55,
    inset 0 1.1875em #555;
}

.mouth::before {
  content: '';
  position: absolute;
  top: -0.25em;
  right: -0.825em;
  width: 3em;
  height: 1em;
  transform: rotate(20deg);
  background-color: #7cd;
  border: 0.125em solid transparent;
  border-bottom-color: #555;
  border-radius: 50%;
}

.mouth::after {
  content: '';
  position: absolute;
  top: -6.5em;
  right: -0.825em;
  width: 2em;
  height: 2em;
  transform: rotate(-20deg) scaleY(0.75);
  background-color: rgba(255,255,255,0.25);
  border-radius: 50%;
  box-shadow:
    -1.5em 0.5em 0 -0.625em rgba(255,255,255,0.25),
    -4.125em 4.5em 0 -0.625em rgba(255,200,200,0.8),
    0.75em 10em 0 -0.5em rgba(255,200,200,0.8);
}

.leg {
  position: absolute;
  z-index: 0;
  top: 50%;
  left: 50%;
  width: 2.5em;
  height: 3em;
  margin: 5.25em 0 0 -1em;
  transform-origin: 50% 1em;
  //transform: rotate(-15deg) translate(-50%,-50%);
  background-color: #7cd;
  border: 0.325em solid #555;
  border-radius: 50% / 50% 50% 50% 30%;
  animation: swing 500ms infinite linear alternate;
}

.leg::before {
  content: '';
  position: absolute;
  bottom: -0.325em;
  right: 0.325em;
  width: 2.25em;
  height: 1.5em;
  transform: rotate(15deg);
  background-color: inherit;
  border: 0.325em solid #555;
  border-radius: 50% 50% 50% 50% / 80% 50% 50% 30%;
}

.leg::after {
  content: '';
  position: absolute;
  width: 100%;
  height: 100%;
  background-color: inherit;
  border-radius: 50% / 50% 50% 50% 30%;
  box-shadow: inset -0.375em 0.25em #6bc;
}

.leg.back {
  z-index: -1;
  width: 2.25em;
  height: 2.75em;
  margin: 5em 0 0 -3.75em;
  //transform: rotate(-20deg) translate(-50%,-50%);
  background-color: #6bc;
  animation-delay: -500ms;
}

.arm {
  position: absolute;
  z-index: 0;
  top: 50%;
  left: 50%;
  width: 2em;
  height: 3em;
  margin: 2.125em 0 0 -0.25em;
  transform-origin: 50% 1em;
  //transform: rotate(-25deg) translate(-50%,-50%);
  background-color: #7cd;
  border: 0.325em solid #555;
  border-radius: 80% 80% 80% 60% / 60% 60% 60% 80%;
  box-shadow: inset -0.375em 0.25em #6bc;
  animation: swing 500ms -500ms infinite linear alternate;
}

.arm.back {
  z-index: -1;
  margin: 1.75em 0 0 -4em;
  //transform: rotate(25deg) translate(-50%,-50%);
  background-color: #6bc;
  animation-name: swing2;
  animation-delay: -1000ms;
}

/* Animation */

@keyframes swing {
  0% { transform: rotate(-60deg); }
  100% { transform: rotate(10deg); }
}

@keyframes swing2 {
  0% { transform: rotate(-10deg); }
  100% { transform: rotate(60deg); }
}

@keyframes bounce {
  0% { transform: translateY(0); }
  100% { transform: translateY(-0.25em); }
}

@keyframes bounce2 {
  0% { transform: rotate(0); }
  100% { transform: rotate(2deg); }
}